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Purple Sweet Potato Pie

yield: 1 nine-inch pie
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Special Equipment

  • A food processor
  • aluminum foil
  • pie weights

Ingredients

For the All-Butter Crust

  • 1/2 cup (4 fluid ounces) very cold water
  • 1/2 cup ice
  • 2 tablespoons apple cider vinegar
  • 1 1/4 cups (5.65 ounces) all-purpose flour
  • 1 1/2 teaspoons granulated sugar
  • 1/2 teaspoon kosher salt
  • 1/2 cup (1 stick // 4 ounces) very cold unsalted butter, cut into 1-inch cubes
  • 1 large egg white
  • 1 teaspoon water

For the Purple Sweet Potato Filling

  • 20 ounces purple sweet potatoes (around 2 medium; see baker's notes for sources)
  • 1 tablespoon freshly squeezed lemon juice
  • freshly grated zest from 1 medium orange
  • freshly grated zest from 1 small lemon
  • 1/2 cup (3.75 ounces) dark brown sugar, tightly packed
  • 1/2 cup (3.5 ounces) granulated sugar
  • 1/4 cup (1/2 stick // 2 ounces) unsalted butter, melted and cooled
  • 1 teaspoon kosher salt
  • 3/4 teaspoon ground cinnamon
  • 1/4 teaspoon ground cardamom
  • 1/4 teaspoon ground nutmeg
  • 3/4 cup (6 fluid ounces) heavy cream
  • 2 large eggs, at room temperature
  • 2 teaspoons pure vanilla extract

For the Crème Fraîche Whipped Cream

  • 1/4 cup (2 fluid ounces) heavy cream
  • 1 tablespoon confectioner's sugar
  • 2 tablespoons crème fraîche

Instructions

For the All-Butter Crust

  • In a liquid measuring cup, combine 1/2 cup very cold water, 1/2 cup ice, and 2 tablespoons apple cider vinegar and whisk to combine. Transfer to the refrigerator to chill while you work with the dry ingredients.
  • In the bowl of a food processor, combine 1 1/4 cups all-purpose flour, 1 1/2 teaspoons granulated sugar, and 1/2 teaspoon kosher salt. Pulse a few times to combine. Sprinkle 1/2 cup very cold cubed unsalted butter over the dry ingredients, and continue pulsing until the butter pieces are about the size of a nickel. Remove the ice water mixture from the fridge and sprinkle 1 to 2 tablespoons over the dry ingredients, pulsing to combine. Continue adding water and pulsing until the butter pieces are about the size of a pea, and the dough sticks together when squeezed and pinched with your fingers.
  • Use a rubber spatula to scrape the dough out into a lightly floured surface and use your hands to shape the dough into a flat disc. Wrap in plastic, and refrigerate for at least 1 hour, preferably overnight.

To Par-Bake the Pie Crust

  • Lightly flour a work surface and transfer your dough from the refrigerator to the surface. Let rest for 10 to 15 minutes, or until pliable enough to roll. Use a rolling pin to roll into a circle about 12 inches wide. Transfer the circle on to a pie plate and fold the edges of the dough to create a rolled border sitting on top of the circumference of the pie plate, using kitchen shears to trim off any excess dough. Use a fork or your fingers to crimp the edges of the crust. Use a fork to prick the bottom and sides of the pie dough, and transfer to the freezer to chill for at least 10 minutes.
  • Meanwhile, center a rack in the oven and preheat to 425 (F). Line a rimmed baking sheet with parchment paper. When the crust is frozen solid, remove from freezer and place on baking sheet. Cover the crust, including the crimped edges, completely with aluminum foil. Pour pie weights into the center of the aluminum foil and spread them so they are more concentrated around the edges of the pie shell. Transfer to the preheated oven and bake for 20 minutes, until the crimped edges are set but not browned. As the pie is baking, whisk together 1 large egg white and 1 teaspoon water.
  • After 20 minutes, remove the pie pan and baking sheet of the oven. Lift the foil containing the pie weights, and let the crust cool for 1 minute. Use a pastry brush to coat the bottom and sides of the crust with egg white glaze. Return the pie pan and baking sheet to the oven's middle rack and continue baking for 3 more minutes. Transfer to a wire rack and cool completely before filling.

For the Purple Sweet Potato Puree

  • Center a rack in the oven and preheat to 400 (F). Line a rimmed baking sheet with aluminum foil. Transfer 20 ounces purple sweet potatoes onto the baking sheet, and use a fork to pierce the sweet potatoes several times throughout their bodies. Bake in the preheated oven for 45 minutes, or until tender and a fork can easily be inserted into the center of each potato without too much resistance.
  • Once the potatoes have been roasted, transfer to a wire rack and cool until they can be handled. Use a knife to cut each potato lengthwise, and peel the skin off each potato. If it's easier, you can also scoop the flesh from each skin — I started out doing this but found that I was losing too much flesh and that it was actually easier to peel off the skins. Once you're done with this process, you should have around 16 ounces of sweet potato flesh. Transfer to the bowl of a food processor and add 1 tablespoon freshly squeezed lemon juice, freshly grated zest from 1 medium orange, and freshly grated zest from 1 small lemon and process until the mixture is very smooth, about 30 seconds to 1 minute.

To Make the Filling and Bake the Pie

  • Center a rack in the oven and preheat to 350 (F). Line a rimmed baking sheet with parchment paper and set aside.
  • In the bowl of a freestanding electric mixer fitted with a paddle attachment, combine 1/2 cup dark brown sugar, 1/2 cup granulated sugar, 1/4 cup melted unsalted butter, 1 teaspoon kosher salt, 3/4 teaspoon ground cinnamon, 1/4 teaspoon ground cardamom, and 1/4 teaspoon ground nutmeg. Beat together on medium speed for 1 minutes, or until all ingredients are combined. Lower the mixer speed to its slowest setting and add 3/4 cup heavy cream, 2 large eggs, and 2 teaspoons vanilla extract, beating until combined. Add the sweet potato puree and continue beating until combined and a homogenous purple color.
  • Scoop the filling into the par-baked pie shell, using an offset spatula to spread evenly across the shell and smooth the top.
  • Transfer the filled pie pan to the prepared baking sheet. Bake in the preheated oven for 30 minutes, or until the filling is puffed and set around the edges but still has a slight jiggle in the center.
  • Transfer to a wire rack and cool completely before covering loosely with plastic wrap and chilling overnight before slicing and serving with whipped cream.

For the Crème Fraîche Whipped Cream

Notes