In the Oven: Sweet Potato Tart with Gingersnap Crust and Heavenly Meringue
Author: 
Yield: One 9-inch tart
 
Ingredients
For the Sweet Potato Puree
  • 3 medium to large sweet potatoes
For the Gingersnap Crust
  • 8 ounces (225 g) gingersnap cookies (about 30 cookies)
  • 2 tablespoons firmly packed light brown sugar
  • 1⁄8 teaspoon kosher salt
  • 2 ounces (½ stick/55 g) unsalted butter, melted
For the Sweet Potato Filling
  • 1⁄3 cup (75 ml) evaporate milk
  • 3 large eggs, at room temperature
  • 1 tablespoon maple syrup
  • 2 cups (480 ml) sweet potato puree (recipe opposite)
  • 1 cup (220 g) firmly packed light brown sugar
  • ½ teaspoon ground cinnamon
  • 1⁄8 teaspoon ground ginger
  • ¼ teaspoon ground nutmeg
  • 1 tablespoon unsalted butter, melted
For the Meringue
  • 3 large egg whites, at room temperature
  • ¾ cup (150 g) granulated sugar
  • ¼ teaspoon cream of tartar
  • ½ teaspoon pure vanilla extract
For the Assembly
  • Ground cinnamon (optional)
Instructions
Make the Sweet Potato Puree
  1. Position a rack in the middle of the oven. Preheat the oven to 400°F (205°C). Line a sheet tray with foil.
  2. Wash the sweet potatoes vigorously with a scrubber. Pat dry and prick the potatoes multiple times with a fork. Place them on the prepared sheet tray. Roast the potatoes until fork tender, rotating the pan halfway through the baking time, about 1 hour. Remove the sheet tray from the oven, place on a cooling rack, and allow the potatoes to cool. Peel and cut them into 1-inch (2.5-cm) chunks, discarding the peels. Puree the sweet potato chunks in a food processor until completely smooth. Add 1 tablespoon water at a time and pulse to reach a typical pumpkin puree–like consistency (thinner than mashed potatoes); this is usually between 1 and 2 tablespoons water. Measure out 2 cups (480 ml) of the puree for the pie and save the rest for another use. (Sweet potato puree lasts 5 to 7 days in the fridge, and 30 days in a freezer bag in the freezer.)
Make the Gingersnap Crust
  1. Preheat the oven to 350°F (175°C). Position a rack in the middle of the oven.
  2. In a food processor, pulse the cookies until pulverized into a very fine crumb. You should have a scant 2 cups (230 g). Add the brown sugar and salt, and pulse until incorporated, about 10 seconds. Pour in the melted butter and pulse until the butter is fully incorporated and the mixture has the consistency of wet sand.
  3. Transfer the mixture to a 9-inch (23-cm) tart pan with removable bottom (or a 9-inch/23-cm springform pan for a smooth-sided finish). Press the crumbs into the bottom and up the sides, using the back of a large spoon or the bottom of a large measuring cup to pack the crumbs into an even layer. Freeze the pan just to set, 8 to 10 minutes. Place the tart pan on a sheet tray and bake until the crust is fragrant and appears set, 6 to 8 minutes. Remove from the oven and cool completely on a wire rack.
Make the Sweet Potato Filling
  1. Turn the oven temperature to 375°F (190°C).
  2. Measure the evaporated milk into a glass measuring cup. Whisk in the eggs and maple syrup.
  3. In the bowl of a standing mixer fitted with the paddle attachment, add the sweet potato puree and mix on the lowest setting to loosen. Add the evaporated milk mixture and beat on medium speed until incorporated, about 1 minute. In a small bowl, stir the brown sugar, cinnamon, ginger, and nutmeg together until combined, then add to the sweet potato mixture and mix on medium speed until just combined. Add the melted butter and mix again.
  4. Pour the mixture into the cooled tart shell. Place the tart on a sheet pan (for easier cleanup in case of seepage), and bake until a toothpick inserted into the middle of the tart comes out clean, 20 to 25 minutes. Cool completely.
Make the Meringue
  1. In a nonreactive metal bowl (ideally the one from your standing mixer), whisk the egg whites and sugar together until combined.
  2. Set the bowl over a saucepan of simmering water. Cook, whisking constantly, until the sugar is completely dissolved and the mixture registers 140°F (60°C) on an instant-read thermometer, to 8 minutes. Remove the bowl from the pan.
  3. In the bowl of a standing mixer fitted with the whisk attachment, beat the mixture on high speed until stiff peaks form, adding the cream of tartar when the meringue begins to thicken, or after minutes. When the mixture holds stiff peaks, after about 6 minutes, add the vanilla and beat to incorporate.
Assemble the Tart
  1. Scoop out the meringue and generously pile it over the top of the tart, swirling and peaking to create your desired look. (You may have some meringue left over.) Use a kitchen torch to gently brown the meringue. (Do not use a broiler.)
  2. To serve, gently push up on the bottom of the tart pan to release it and transfer it to a plate or stand. Dust with a light coating of cinnamon before slicing, if you like.
Notes
How to store: The tart tastes best if eaten within 24 hours but can be kept, covered, in the refrigerator for up to 2 days.
Recipe by Baked Sunday Mornings at http://bakedsundaymornings.com/2016/11/10/oven-sweet-potato-tart-gingersnap-crust-heavenly-meringue/