Sweet potatoes make a mouthwatering, creamy custard for the filling in this lightened-up pie with an easy gluten-free cookie crust. Serve with a dollop of whipped cream for dessert.
Preheat oven to 400 degrees F.
Tightly wrap sweet potatoes in foil and place on a baking sheet. Roast until very tender, about 1 1/4 hours. Carefully unwrap and set aside to cool. (Alternatively, poke holes in sweet potatoes with a knife or fork. Microwave on High until tender, 10 to 12 minutes.)
Reduce oven temperature to 350 degrees F.
Process gingersnaps in a food processor until finely ground. Transfer to a bowl, add 3 tablespoons melted butter and stir until well combined. Using a spoon, spread and pat the crumbs into the bottom and up the sides of a 9-inch pie pan. Bake until barely beginning to darken, 6 to 8 minutes.
Clean and dry the food processor work bowl. Peel the sweet potatoes and transfer to the food processor. Puree until smooth. Measure out 1 1/2 cups (if you have extra puree, reserve it for another use). Return the 1 1/2 cups of puree to the food processor. Add the remaining 2 tablespoons melted butter, brown sugar, evaporated milk, eggs, vanilla, cinnamon, nutmeg and ginger; pulse until just combined. Spread the filling in the warm crust.
Bake the pie until firm to the touch and starting to puff around the edges, 35 to 45 minutes. Let cool completely on a wire rack, at least 3 hours.
Make-Ahead Tip: Loosely cover the pie and refrigerate for up to 1 day. Let stand at room temperature for 30 minutes before serving; blot any moisture on top as needed.
1 fat, 1 other carbohydrate, 1/2 starch, 1/2 starchy vegetable