Step 1

To make the sweet potato puree, cover sweet potatoes with water in a large saucepan. Bring to a boil; cook until tender when pierced with the tip of a paring knife, about 15 minutes. Drain; puree in a food processor until completely smooth. Let cool completely before using (refrigerate or freeze for quicker cooling).

Step 2

To make filling, preheat oven to 375 degrees. In a large bowl, whisk eggs, 1/3 cup brown sugar, and maple syrup until smooth. Add sweet-potato puree, salt, cinnamon, nutmeg, and 3/4 cup cream; whisk until completely smooth. Place cooled crust on a rimmed baking sheet; pour filling into crust. (If using a store-bought crust, defrost 10 minutes; prick bottom all over with a fork.)

Step 3

Bake pie on lowest rack of oven until filling is set, about 50 minutes. If crust browns too quickly, tent edges with foil. Transfer pie to a rack to cool, 1 hour; transfer to refrigerator to cool completely.

Step 4

To make the pecan topping, melt butter over medium heat in a medium saucepan. Add remaining 1/2 cup light-brown sugar and pecans. Cook, stirring, until sugar is incorporated and the mixture is smooth, about 3 minutes. Stir in remaining tablespoon cream; let cool 1 to 2 minutes. Pour mixture over cooled pie. With a butter knife or spatula, spread mixture over pie. Cool until topping has hardened, about 30 minutes. (Do not refrigerate again; keep pie in a cool place up to 6 hours.)