Sweet Potato Meringue Pie

Preparation

1. Step 1

   On a lightly floured surface and using a lightly floured rolling pin, roll out a disk of dough into a circle about ¼-inch thick. Starting at one end, gently roll up the dough onto the rolling pin. Unfurl the dough over a 9-inch pie plate, preferably ceramic, and press it in lightly, making sure it’s lining the plate.

2. Step 2

   Trim so that there’s about ½ inch of excess dough hanging over the edge of the pie plate. (If the dough feels warm, refrigerate it for 15 minutes.) Tuck the excess dough under itself so it is flush with the edge of the pie plate; leave the pie like this for a straight-edge finish, or crimp as desired. Dock the base and sides all over with a fork and refrigerate at least 30 minutes, and up to 2 hours.

3. Step 3

   Place a rack on the bottom shelf of the oven, and place a baking stone, if you have one, on the rack. Heat the oven to 425 degrees. Use a small brush to evenly paint egg wash on the edge of the crust. Cut a square of parchment paper and use it to line the crust. Fill with pie weights (or dried beans) up to the top edge. Place the plate on a baking sheet lined with parchment or foil.

4. Step 4

   Transfer the baking sheet to the oven, placing it directly on the baking stone if using. Bake crust until the outer edge is just starting to turn golden brown, 12 to 15 minutes. Remove the parchment and pie weights, and continue to bake until the base appears set, 2 to 4 minutes more. If the dough puffs up anywhere, you can puncture it with a fork. Cool the crust completely. Reduce the oven temperature to 375 degrees.

5. Step 5

   Make the filling: In a medium bowl, whisk the eggs, brown sugar, granulated sugar, vanilla and melted butter to combine.

6. Step 6

   Add the sweet potatoes, cinnamon, ginger and nutmeg and mix to combine. Whisk in the heavy cream until evenly incorporated. (If you have an immersion blender and want to get the texture even smoother, you can blend it now too.) Transfer the pie plate to the prepared baking sheet and pour the custard into the crust.

7. Step 7

   Transfer the baking sheet to the oven, placing it directly on the baking stone if using. Bake until the crust is evenly golden brown and the custard appears set around the outer edge, about 35 minutes; the center of the pie may still be noticeably jiggly. Let cool completely at room temperature on a rack.

8. Step 8

   Make the meringue: Place the egg whites and cream of tartar in the bowl of an electric mixer fitted with the whisk attachment and mix briefly just to combine. Stir the sugar and ⅓ cup/80 milliliters water together in a small pot. Place the pot over medium heat, and stir until it begins to simmer, then stop stirring. Use a pastry brush dipped in water to brush away any sugar crystals that have washed up on the sides of the pot.

9. Step 9

   Continue to cook the sugar mixture until it reaches 235 degrees on a thermometer, about 4 to 5 minutes; when it does, start whipping the egg whites on medium speed. (The goal is to get them lightly whipped and foamy by the time the sugar reaches 240 degrees.)

10. Step 10

    When the sugar reaches 240 degrees, remove the pot from the heat. With the mixer still running on medium speed, gently pour the sugar syrup down the side of the bowl in a slow, steady stream. Continue whipping until the meringue reaches medium peaks, 3 to 4 minutes more.

11. Step 11

    Prepare two disposable piping bags by cutting openings large enough to accommodate pastry tips: an open star tip and a French star tip. Divide the meringue between the two bags.

12. Step 12

    Starting with one of the bags, pipe shapes on top of the filling around the outside edge of the pie, varying the shapes in size and design. (Piping straight downward will form a basic star shape, or you can pipe in a spiral to create a sort-of rosette design.) The piped shapes should be random and can be layered on top of one another for the fullest look. Continue with both bags until the whole outer portion of the pie is covered, leaving a 3-inch circle of filling exposed in the center. (You’ll most likely have extra meringue: See Note.) Alternatively, you can skip the piping, and scoop the meringue onto the pie, swirling it with the back of a spoon or offset spatula.

13. Step 13

    Use a kitchen torch to toast the meringue, if desired. Serve within 2 hours. Store leftovers in the refrigerator, tented with foil.