Rhubarb Custard Pie

Rhubarb Custard Pie

Most American rhubarb pie recipes are plain and simple—just tangy rhubarb fruit encased in buttery pie crust. While plain old rhubarb pie is still a pretty good dessert, I wanted to take my rhubarb pie to the next level. What does that mean? I combined the tart and tangy rhubarb fruit with a sweet cream custard to make this beautiful rhubarb custard pie!

However, I’m not actually the innovator of this particular flavor combination. British recipes frequently pair rhubarb and custard together in desserts. Indeed, over the years, I’ve watched many Great British Bake-Off contestants whip up beautiful rhubarb custard desserts. And I have fond memories of watching one of my British friends whip up a rhubarb custard frangipane galette for a dinner party.

But hold the phone. What exactly is rhubarb, anyway?

What is Rhubarb?

Rhubarb is a long, thin vegetable that looks a little bit like celery. Both celery and rhubarb are sold as stalks. However, unlike celery, rhubarb is know for its distinct pink color. That being said, rhubarb comes in a range of colors. Some stalks have pale greenish-pink hues, while others range from stronger pastel pinks to deep, magenta reds.

Wait—you said rhubarb is a vegetable. Is rhubarb a fruit or a vegetable?

Yes, technically, rhubarb is a vegetable. Why? Botanically speaking, fruits are the result of seed-bearing plants, whereas vegetables come from other plant parts like roots, leaves, and stems. And culinary rhubarb comes from the stem of a rhubarb plant (Not the leaves though—those are inedible and poisonous! We’ll get to that in a second).

That being said, rhubarb is technically classified as a fruit. What does that mean, exactly? According to this Huffington Post article, in 1947, a New York court declared rhubarb a fruit for tax-saving purposes. Back then, importers of fruit were charged less taxes than importers of vegetables. Lawyers successfully argued that rhubarb should be declared as fruit because rhubarb most often used and prepared in sweet dishes. Wild, right?

I’m still distracted about what you said about rhubarb being poisonous. Is rhubarb poisonous?!

Hahaha, yep, parts of the rhubarb plant are poisonous! Specifically, rhubarb leaves contain high amounts of oxalic acid, which can cause kidney failure in humans. Eating even a small amount of rhubarb leaves can cause diarrhea and vomiting. Yikes.

Thankfully, the part of the rhubarb plant that we eat and use for baking and cooking—the stem—is safe and sound. Just be sure that, if you purchased fresh rhubarb for this recipe, you trim off any leaves as well as the top of the stalk before using!

What does rhubarb taste like?

Uncooked, raw rhubarb is VERY tart, sour, and acidic. Like, almost inedibly so. As a result, almost all recipes instruct you to cook the rhubarb and serve it with a generous amount of sugar. Even after the fact, rhubarb retains a lot of its tartness. I like to think of its flavor as similar to tart green apples or unsweetened cranberry juice… but also not really, lol. Rhubarb definitely has its own flavor that’s worth trying!

What Does Rhubarb Custard Pie Taste Like?

Because if its tart flavor, rhubarb works really well with sugar and dairy. Like in this rhubarb custard pie!

Without the rhubarb, the sweet cream custard tastes like a traditional buttermilk chess pie. But because this pie is made with cream instead of buttermilk, it lacks any kind of tangy, acidic flavor. Think of it as similar to vanilla ice cream, but baked in a buttery pie crust shell. Sounds delicious but intense, right?

Enter the rhubarb fruit topping! The rhubarb acts like the buttermilk in traditional chess pie recipes and brings tart, tangy flavors to the whole pie. Without the rhubarb, the sweet cream custard filling would be too rich on its own.

Does classic rhubarb custard pie have a top crust?

No, I don’t think so? When researching different rhubarb custard pie recipes to try for this post, I noticed that 9 out of 10 of them didn’t have top crusts. I suspect it has to do with the custard—other custard based pies like chess pies, key lime pies, and more rarely have top crusts, either.

That being said, I did see a handful of recipes that made the pie with a top crust. Upon close inspection though, it seemed like these pie recipes were more akin to traditional rhubarb pies than rhubarb custard pies? I don’t know, you do you. I’m sure a top crust would be delicious!

Why You Should Make This Rhubarb Custard Pie Recipe

Here are all the reasons why you should make this rhubarb custard pie recipe:

This rhubarb custard pie recipe comes together quickly.

Thanks to the store bought crust, this rhubarb custard pie recipe is fast and easy. Beyond baking the pie crust and the assembled pie itself, all you really need to do is chop up the rhubarb and make the custard filling. And those tasks only take 10 minutes… combined! Crazy, right?

This rhubarb custard pie recipe is from a trusted recipe source: Martha Stewart!

Contrary to popular belief, I do not develop all the recipes on this blog from scratch. Some are from other sources—usually cookbooks, magazines, and other food blogs—that I’ve wanted to try for myself. Like this rhubarb custard pie recipe! This particular recipe comes from the queen herself, Martha Stewart. And of course, because Martha is Martha, it’s absolutely delicious and does not disappoint.

This rhubarb custard pie recipe has ingredients that can be easily substituted with other similar ingredients.

One of the reasons why I was drawn to this rhubarb custard pie recipe in the first place was because I noticed that its ingredients were extremely adaptable. What does that mean? In theory, if you find yourself missing a certain ingredient, you can easily swap it out for something that you already have on hand. This will prevent you from having to make a last minute run to the grocery store, and encourage you to make do with what you have in your pantry. Be sure to check out the ingredients section below for all my substitution recommendations!

Rhubarb Custard Pie Ingredients (and Their Substitutions)

Now that I’ve convinced you to make this rhubarb custard pie recipe, let’s talk about some of its key ingredients:

Store-Bought Pie Crust

This rhubarb custard pie recipe uses a store-bought pie crust for its pie crust base.

Types of store-bought pie crust

Typically, grocery stores sell two different types of store-bought pie crust. The first kind is where the dough is rolled up in a sheet, and you need to do the work of fitting it onto the pie plate yourself. The second kind is where the dough is already molded onto a pie plate (usually one made of disposable aluminum), and all you need to do is fill it. Depending on the brand, you end up with either an 8-inch or 9-inch pie. For this rhubarb custard pie recipe, I used the latter kind where the pie dough has already been fitted into a plate.

Why use store-bought pie crust?

As much as I hate love making pies from scratch (I mean… remember that time I spent the year making a different kind of pie per month?), I recently finished Nadiya’s Time to Eat on Netflix and was inspired to make this recipe more accessible.

In the show, the lovely host Nadiya Hussein (and winner of The Great British Bake-Off in 2015) teaches time-poor families and individuals on how to cook tasty and delicious meals quickly and on a budget. Despite being one of the UK’s most talented bakers, Nadiya actively encourages folks to use store-bought shortcuts like premade pastry dough, canned fruits and vegetables, and more. That way, folks could still end up with delicious, beautiful meals without spending hours in the kitchen.

I was inspired by how accessible Nadiya’s recipes were and decided to stop being so snotty about making pie dough from scratch. Indeed, with a store-bought pie crust, this recipe came together SO quickly. Like… seriously. I think it took less than 5 minutes to prep the pie dough for the filling, and another 5 minutes to make the filling itself? The rest of the time was spent waiting for the pie to finish baking in the oven!

Best store-bought pie crust

Confession: I am not the best person to answer this question. I always use the generic store-bought pie crust from Safeway because I like the way they crimp its edges (they look like these ones from Marie Callender’s). But is it the best tasting? I really don’t know. Instead, I encourage you to check out these articles from Epicurious and The Kitchn that compare different store-bought pie crusts under the same filling.

How to make store-bought pie crust better

Okay, so you read the last few paragraphs above and are looking at me with disbelief. But store-bought pie crust is so bad, I hear you thinking. Why are you making me do this?! I admit: it’s hard to compare store-bought pie crust to homemade flaky, all-butter pie dough made from scratch. But here’s the thing—good recipes transcend bad ingredients. That is, an amazing pie filling like this rhubarb custard will cover up a mediocre pie crust.

And besides, there are a lot of tips and tricks to make store-bought pie crust better. The crazy talented Shauna Sever likes to pulse up cookie crumbs and add them to the dough for an extra layer of crunchiness. And in this recipe, I instruct you to ignore the manufacturer’s instructions for pre baking the pie crust. Why? My method results in an infinitely crisp pie crust with no soggy bottom. But we’ll learn more about that in a second.

Can I make this rhubarb custard pie recipe with store-bought gluten-free pie crust?

Yes, absolutely! But note that the filling itself is not actually gluten-free. The custard filling uses ⅓ cup all-purpose flour. Check out the flour section below to read about possible substitutions and ways to potentially make it gluten-free.

Also note that I have never pre baked a store-bought gluten-free pie crust before. My instructions for pre baking might not work for the gluten-free pie crust. You may want to stick with the manufacturers’ instructions for pre baking instead.

Can I make this rhubarb custard pie recipe with homemade pie crust from scratch?

Yes, absolutely! If you’re looking for an easy, all-butter homemade pie crust recipe to use for this rhubarb custard pie, I recommend checking out the one in my cookbook, Weeknight Baking. It’s seriously my best and favorite recipe for pie dough. I instruct you to make the pie dough in a stand mixer like you would a sugar cookie dough to bring it together. It’s much easier than fussing around with a pastry cutter or hauling out your food processor for the job!

Intrigued? You can see a sneak peek of the recipe in this recipe for chocolate chess pie. However, I definitely encourage you to check out the full thing in my book. The cookbook has a lot more tips and tricks to make the pie crust work for you!

Rhubarb

This rhubarb custard pie recipe uses 1 pound fresh rhubarb.

Can I use frozen rhubarb?

Yes! You can use frozen rhubarb in this rhubarb custard pie recipe. As long as the rhubarb has been sliced into ½-inch pieces, there’s no need to even thaw the frozen rhubarb before using in this recipe!

However, if you make this pie with frozen rhubarb, it’s likely that you’ll need to add 5 to 10 minutes to the Bake Time to fully cook the cold fruit.

How to Freeze Leftover Rhubarb

Uh oh, you bought too much rhubarb and now have some left over. No worries—rhubarb freezes wonderfully! Before freezing, I like to clean the fruit thoroughly. I then slice the rhubarb stalks into ½- to 1-inch pieces. Why? It’s very rare that recipes—especially baking recipes—use whole rhubarb. Many recipes call for the rhubarb to be sliced into ¼-, ½-, and 1-inch pieces. After slicing the fruit, transfer it to a freezer zip top bag. Squeeze all the air out of the bag and freeze for up to 1 year.

Now… what can you do with that frozen rhubarb? Good question! Check out the bottom of the blog post for links to other rhubarb recipes on my blog!

Can I use another fruit besides rhubarb for this rhubarb custard pie recipe?

Yes! You can either swap out part of the rhubarb with another fruit (like strawberries, to make a strawberry rhubarb pie!), or replace it completely. However, some fruits will work better than others. I suggest swapping the rhubarb out with a berry—I recommend strawberries, blueberries, and raspberries. I do not recommend any kind of stone or stem fruit. Their flavors and textures won’t work as well with the custard base.

Granulated Sugar

This rhubarb custard pie recipe uses 1 ½ cups granulated sugar. Note that you’ll need to divide the sugar into two portions. Use ¼ cup to prep the rhubarb, then the rest for the custard filling.

Can I use brown sugar or coconut sugar instead of white sugar in this rhubarb custard pie recipe?

Yes! You can use either light or dark brown sugar for this rhubarb custard pie recipe, along with coconut sugar.

Can I use a non-refined sugar alternative like stevia or xylitol granules in this rhubarb custard pie recipe?

Yes! However, it’s likely you’ll need to reduce the quantity that’s listed in the recipe. Both 1 tablespoon of stevia and xylitol are sweeter and more flavorful than 1 tablespoon of granulated sugar. Unfortunately, I do not know the exact amount for the substitution. I rarely bake with artificial sweeteners as I don’t have any special dietary restrictions.

That being said, you can figure it out on your own! Follow the recipe instructions to whisk all the ingredients of the custard together except for the artificial sweetener of your choice. Once you’ve got the custard base going, add ¼ cup of the sweetener. Whisk vigorously and taste the custard—if it doesn’t taste sweet enough for you, add another ¼ cup, whisk and taste again. Keep doing this until you achieve your desired level of flavor. This is what us recipe developers do! Cool, right?

All-Purpose Flour

This rhubarb custard pie recipes uses ⅓ cup all-purpose flour.

I want to use a whole wheat flour instead. Is that possible to do in this rhubarb custard pie recipe?

Technically yes, but I don’t recommend doing so. Like I said—technically, you can substitute out the all-purpose flour completely with the same amount of whole wheat flour. You may need to increase Bake Time by a few minutes since baked goods with whole wheat flours typically require more Bake Time.

That being said, I don’t think it’s a good idea to do so. Using whole wheat flour will result in a darker custard that will affect the way the rhubarb stands out in the pie. The custard will also likely be heavier—its texture will no longer be light and creamy like traditional custard.

What about other alternative, gluten-free nut flours like almond meal or almond flour?

No, I don’t recommend swapping out the all-purpose flour with almond meal or almond flour in this rhubarb custard recipe. The gluten in all-purpose flour helps thicken and set the custard filling. Without it, the pie will likely loose its shape when sliced, causing filling to gush out everywhere. If you want to make the filling gluten-free, you’ll need to use a gluten-free alternative with thickening properties. Check out some ideas below!

I don’t eat gluten. How can I make the rhubarb custard pie filling gluten-free?

You can replace the all-purpose flour recipe with a gluten-free thickener like corn starch, potato starch, tapioca starch, and more. However, note that these thickeners have twice the thickening power of all-purpose flour itself. You’ll need to reduce the quantity to use. I would start by replacing the ⅓ cup of all-purpose flour with 5 tablespoons of cornstarch or the starch of your choice.

That being said, I haven’t personally tried this substitution myself. I cannot 100% guarantee its results. If you try my suggestion, please report back by leaving a comment below!

I don’t eat gluten. Does a 1-1 gluten free all-purpose flour (like Bob’s Red Mill, or King Arthur Flour) work in this recipe?

I’m sorry, but I don’t know. I rarely bake with those types of flour replacements because they’re expensive and my household doesn’t have any gluten restrictions. That being said, if you’ve successfully used 1-1 gluten free all-purpose flour replacer in other, similar pie or custard recipes, it’s likely to work in this recipe too! Why? This custard recipe doesn’t really vary too much from the norm—it’s a fairly standard recipe. Just let me know so I can update this post accordingly!

In general, my specialty lies in creating baking recipes with conventional ingredients. If you’re looking for a gluten-free pie recipe, I suggest checking out my friends over at The Bojon Gourmet and Snixy Kitchen. Both Alanna and Sarah specialize in gluten-free baking and will be able to help you out better than I can!

Heavy Cream

This rhubarb custard pie recipe uses ¼ cup heavy cream in this recipe.

I don’t have heavy cream. What can I use instead?

In a pinch, you can also use light whipping cream or whole milk. However, I do not recommend using low- or nonfat milk. If you do, it’s likely that the custard won’t set properly (all that fat is necessary in order for it to do so!). You’ll also likely end up with a less flavorful custard filling.

Can I use a non-dairy alternative for the heavy cream?

Yes! You can substitute the heavy cream out with the same amount of full fat canned coconut milk.

Note that there are many types of coconut milk available in grocery stores. You can buy shelf-stable coconut milk in cans, or perishable coconut milk in cartons in the refrigerated aisle. For baking and cooking, it’s best to stick with canned coconut milk—that’s usually what recipes mean when they call for “coconut milk”. Be sure to shake the coconut milk can well before using in the recipe!

How to Make Rhubarb Custard Pie

Here are the basic steps to make rhubarb custard pie from scratch:

First, prep the main ingredients:

1. Pre bake the store-bought pie crust. (Bake Time: 30 minutes)
   When a recipe instructs you to pre bake a pie crust, that usually means that the pie’s crust and filling have different baking times. One will need to bake for longer in the oven to be considered done (typically, it’s the crust takes longer to cook than the filling). This is often the case for pie recipes with custard fillings, like pumpkin pie or this rhubarb custard pie. Pre baking the crust for those types of pies will give the pie crust a head start by partially baking it; by the time you add the filling to the partially baked crust, both the crust and the filling will be done all at the same time.
   
   I typically pre bake my pie crust for longer than what’s instructed on the packet. Doing so makes a crispier pie that prevents the custard filling from making the bottom soggy. Furthermore, after it’s done baking, I “glaze” the bottom and sides of the crust with egg wash and then bake it for another 5 minutes. In the oven, the egg wash hardens into a shiny, lacquered shell that “waterproofs” the crust even further.
   
   
2. While the crust is in the oven, prep the rhubarb. (Prep Time: 5 minutes)
   While the crust is baking in the oven, I like to prep the rhubarb by cleaning and slicing it for use in the filling. I then toss the rhubarb in ¼ cup of granulated sugar. Why? The sugar encourages the rhubarb to soften and release some of its fruit juice, making it more flavorful and toothsome. This process is called maceration. Cool, right?
   

Next, make the custard filling:

1. Once the pie crust is done pre baking, make the custard. (Work Time: <5 minutes)
   I mentioned before that making the custard takes less than 5 minutes. Simply whisk together the remaining sugar, flour, eggs, butter, and cream until thick and creamy. That’s it!
   
   
2. Assemble the pie. (Work Time: <5 minutes)
   Pour the custard into the pre baked pie crust, then top with the prepared rhubarb. Again, this entire process only takes about a minute or so.
   
   
3. Bake the pie. (Bake Time: 60 minutes)
   Baking the pie is the most time-consuming part of the recipe. The pie bakes for about 60 minutes, just until the edges are set but the center wobbles ever so slightly when gently tapped.

Rhubarb Custard Pie Recipe Troubleshooting

FAQ: Rhubarb Custard Pie Ingredients

Can I make this rhubarb custard pie recipe gluten-free?

Yes! You can make a gluten-free rhubarb custard pie with this recipe. Simply use the gluten-free store bought pie crust of your choice. You may need to pre bake the pie crust to the manufacturers’ instructions since I don’t know if my instructions below work for gluten-free pie crusts. Then, make the filling, but use 5 tablespoons of cornstarch (or potato or tapioca starch) instead of all-purpose flour.

FAQ: Equipment for Making Rhubarb Custard Pie

What are pie weights and why do I need to use them in this rhubarb custard pie recipe?

This rhubarb custard pie recipe instructs you to cover the unbaked pie crust with aluminum foil, then pour in pie weights on top of the foil and bake the whole thing. The pie weights weigh the pie crust down as it bakes, preventing any air bubbles underneath the pie crust to rise up and cause weird bumps in the crust. The pie weights also weigh down the dough so that it holds its shape and stays molded onto the pie plate as it bakes. Without them, your pie crust will likely shrink and sag down the pie plate.

Okay, you’ve convinced me to buy pie weights. I’m confused. There are so many different kinds… help!

Yes, on Amazon, there’s an astonishingly large variety of pie weights. Most can be divided up into two categories: ceramic balls, and metal chains.

Avoid the metal chains at all costs!!! In theory, you coil the chain around itself to form a circle inside the pie crust. The chain is easier to use than the pie weights because you can lift it out all at once. However, in practice, the chains is often almost too lightweight. What does that mean? It is too light to hold down your pie crust properly—you’ll end up with bumps in the bottom of the pie crust, and sides that have shrunken and slid down the pie pan.

It’s better to invest in the heavier ceramic weights. The more you have, the better too. I have a pair of these pie weights and am considering getting a third box. To lift them out, I simply line the pie crust with a sheet of parchment paper or aluminum foil. I pour the weights on top of the parchment/foil, then use the parchment/foil to lift them out all at once when done. Be careful—they’ll be hot!

I don’t have pie weights. Can I use something else?

Yes, you can! Although I like the ceramic pie weights I recommend above, sometimes I’m too lazy to pull out the stool to get them from the top shelf of my baking cupboard. So what do I do instead? I use other common household or pantry items in their place.

My favorite trick (that you can watch me do in the Instagram Story tutorial for this recipe) is to use the loose coins in my spare change jar. Instead of pouring the ceramic pie weights in, I pour in a generous amount of coins. Coins are heavier than the ceramic pie weights, and do an even better job of holding the crust in place.

If you are a sensible person who uses all your coins, you can also use uncooked dried beans or raw rice. According to this Kitchn article, however, it’s best not to cook the beans after—they have a funny flavor. The rice, however, remains perfectly edible. Pretty cool.

FAQ: How to Store Rhubarb Custard Pie

Can you freeze an unbaked rhubarb custard pie?

Sadly, no. It’s best not to freeze unbaked cream or custard pies. The cream and custard fillings tend to get watery and separate as they thaw. Let’s avoid that, please!

Does baked rhubarb custard pie need to be refrigerated?

Yes! Because the filling is cream-based, I suggest refrigerating this pie. After baking, I like to let the pie cool completely. Doing so will crisp up the crust and firm up the custard pie filling perfectly. After that, I cover with a loose sheet of plastic wrap and refrigerate for up to 3 more days.

Can baked rhubarb custard pie be frozen?

Yes! Follow the recipe instructions for cooling the pie completely to room temperature. After that, tightly wrap the entire pie (or any leftovers!) in two layers of plastic wrap and freeze for up to 3 months.

To serve, thaw overnight in the refrigerator. Serve chilled, or reheat in the microwave or by baking in the oven at 350°F for 10 to 15 minutes or until a knife inserted into the center of the filling comes out warm.

More Rhubarb Recipes

• Pistachio, Rosewater, and Rhubarb Semolina Cake
• Rhubarb Marzipan Upside Down Cake
• Rhubarb Panna Cotta Tart
• Rhubarb and Pistachio Pavlova
• Rhubarb and White Chocolate Blondies

More Custard Pie Recipes

• Blueberry Almond Custard Pie
• Chocolate Chess Pie
• Funfetti Buttermilk Chess Pie
• Maple Lime Custard Pie
• Meyer Lemon Chess Pie

Rhubarb Custard Pie Recipe

yield: 1 8-inch pie

Prep Time: 5 mins

Work Time: 10 mins

Bake Time: 1 hr 30 mins

5 from 4 votes

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Ingredients

For the Pie Crust

• 1 frozen store-bought pie crust in a pie plate
• 1 large egg white
• 1 teaspoon water
• pinch of kosher salt

For the Rhubarb Custard Pie Filling

• 1 pound (or 454 grams) fresh rhubarb, sliced into ½-inch chunks
• 1 ½ cups (10.5 ounces or 298 grams) granulated sugar, divided into ¼ cup (1.75 ounces or 50 grams) and 1 ¼ cup (8.75 ounces or 248 grams) portions (see baker's notes)
• ⅓ cup (1.5 ounces or 43 grams) all-purpose flour
• 2 large eggs
• 4 Tablespoons (2 ounces or 57 grams) unsalted butter, melted
• ¼ cup (4 ounces or 113 grams) heavy cream

Instructions

For the Rhubarb Custard Pie

• First, pre bake the crust: Position a rack in the center of the oven and preheat the oven to 375°F. Line a sheet pan with parchment paper and place the frozen crust in the center of the pan. Cover the crust with foil, making sure the crimped edges are completely covered and there are no gaps between the foil and the crust. Fill with pie weights and spread them out so they are more concentrated around the edges of the crust.
• Bake for 25 minutes. While the crust is in the oven, make the egg wash for the pie crust: in a small bowl, whisk together the egg, water, and salt. Prep the rhubarb for the filling by placing it in a medium bowl and tossing it in ¼ cup (1.75 ounces or 50 grams) granulated sugar.
• Once the pie is done, remove the sheet pan from the oven, keeping the oven on. Carefully lift out the pie weights and the foil. Use a pastry brush to coat the bottom and sides of the pie crust (but not the crimped border) with a thin layer of egg wash. Bake, uncovered, for an additional 5 minutes. Cool on a wire rack while you make the custard filling.
• Next, make the custard filling: Whisk together the remaining 1 ¼ cup (8.75 ounces or 248 grams) sugar, flour, eggs, butter and cream until combined. Pour the filling into the prepared crust and scatter the rhubarb evenly on top, discarding any liquid at the bottom of the bowl.
• Bake for 60 to 65 minutes, or until the edges of the filling are set but the center still wobbles slightly. Cool on a wire rack. Serve warm or at room temperature. The pie can be stored at room temperature until ready to serve. After that, cover loosely with plastic wrap and refrigerate for up to 3 days.

Notes

Rhubarb custard filling recipe adapted from Martha Stewart 

This post was last updated on 5/31/2020.

NO TIME TO BAKE?!

Over the past several years of running Hummingbird High, I kept a crucial aspect of my life hidden from my readers: I had a full-time, extremely demanding job in the tech world. In my debut cookbook, Weeknight Baking, I finally reveal the secrets to baking delicious desserts on a tight schedule.

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