Preheat oven to 400°F (200°C). Prick whole sweet potatoes with a fork and roast on a foil-lined baking sheet for 50 to 60 minutes until completely tender. Cool, peel away skins, and mash the flesh until ultra-smooth (or puree in a food processor to remove any fibers).

Roll out pie dough into a 9-inch deep-dish pie plate, crimp edges, and chill in the refrigerator for 20 minutes. Brush bottom of crust lightly with beaten egg white to prevent sogginess.

Reduce oven temperature to 350°F (175°C).

In a large mixing bowl with an electric hand mixer on medium speed (or in a stand mixer), beat the roasted sweet potato puree and melted butter for 2 minutes until glossy and combined.

Add granulated sugar, brown sugar, beaten eggs, evaporated milk, vanilla extract, cinnamon, freshly grated nutmeg, ginger, salt, and flour. Beat on medium-low speed until the custard is completely smooth, airy, and creamy.

Pour the spiced sweet potato filling into the prepared pie crust, smoothing the surface with a spatula.

Place pie plate on a rimmed baking sheet. Bake at 350°F (175°C) for 50 to 55 minutes until the edges of the filling are puffed and set, and the center has a gentle, subtle jiggle when nudged.

Transfer pie to a wire cooling rack and cool completely to room temperature (about 2 to 3 hours). The custard will finish setting as it cools.

Chill in refrigerator for at least 2 hours before slicing with a clean, sharp knife. Serve with homemade bourbon whipped cream and a dusting of nutmeg.