1/4cup(1/2 stick) unsalted butter, melted and cooled
2 1/4teaspoonswater
Instructions
For the Rhubarb Curd
Place 8 ounces trimmed and chopped rhubarb in a small, heavy-bottomed sauce pan with enough water just to cover the rhubarb. Scrape the vanilla seeds from the 1/2 vanilla bean pod into the mixture, before throwing the pod into the mixture as well. Bring to a boil, then simmer for about 20 minutes until the rhubarb is soft and you have a pink juice. Strain out rhubarb pieces and vanilla pod and let cool. Measure out 2/3 cup of juice for the curd.
In another medium, heavy-bottomed sauce pan, whisk together 2/3 cup rhubarb juice (from the 1st step), 2/3 cup sugar, and 4 large eggs. Cook over medium-low heat, stirring constantly and scraping the sides and bottom of the pot with a wooden spoon, just until the internal temperature reaches 170 (F). If you don't have a thermometer, watch for the mixture to thicken until it is able to coat the back of the spoon.
Once the mixture has reached 170 (F) and coats the back of a wooden spoon, remove from heat and whisk in 1/2 cup unsalted, cubed butter a few pieces at a time, only adding the next cubes when the cubes before have melted. Once all the butter has been added, strain through a fine mesh sieve and allow to cool to room temperature.
Once the curd has cooled to room temperature, cover and refrigerate for at least 2 hours until firm. The rhubarb will keep in an airtight container in the fridge for up to 2 weeks.
For the Pie Crust Crumble
Preheat the oven to 350 (F). Prepare a baking pan by lining with parchment paper or a Silpat mat.
Add 1/4 cup melted butter and 2 1/4 teaspoons water on low speed until the mixture starts to come together in small clusters.
Spread the clusters on the prepared baking pan and bake in the preheated oven for 25 minutes, using a bench scraper to break the clusters up occasionally. After 25 minutes, the crumbs should be golden brown and slightly moist to the touch — they will dry and harden as they cool. Allow the crumbs to cool to room temperature on their baking sheet in a wire rack.
Let the crumbs cool for about 10 - 15 minutes, before sprinkling in a bowl of rhubarb and meringues. However, the crumbs will keep fresh for up to 1 week at room temperature if stored in an airtight container.