Preparation

• 在一个中等大小的平底锅,combine the sweet potatoes, cinnamon stick pieces, cloves, star anise, and ginger slices with enough water to just cover the contents. Bring to a boil over high heat. Reduce the heat and simmer uncovered until the sweet potatoes are very tender when pierced with a fork or skewer, about 10 minutes. Drain the potatoes, reserving the boiling liquid. Return the potatoes to the pot over low heat and toss to dry them a bit. Discard the cinnamon, cloves, and star anise. Force the warm potatoes through a ricer, a food mill, or a sieve. Boil the liquid if needed, until reduced to 1/4 cup. Let the sweet potato mash and the liquid cool.
• Position an oven rack in the lower half of the oven; heat the oven to 350°F. In a large bowl, whisk together the pumpkin and sweet potato purée. Whisk in the egg, egg yolk, melted butter, and reserved spiced liquid. In a separate bowl, stir together the granulated and brown sugars with a wire whisk until any large lumps of brown sugar are gone. Sift the flour and salt over the sugars; stir to blend. Add the sugar-flour mixture to the pumpkin and stir well until no pockets of sugar are visible. Blend in the coconut milk.

• Scrape the filling into the chilled pie shell; smooth the top. Bake for 1-3/4 to 2 hours, turning the pie several times so it bakes evenly. The point of a thin-bladed knife should come out clean when inserted into the center of the filling, and the edges of the surface will be unevenly cracked. If the edges of the pastry darken too much before the filling is cooked, cover them with a pie shield or strips of aluminum foil. Transfer the pie to a wire rack and let cool completely before serving with mounds of the lightly sweetened whipped cream.

Make Ahead Tips

The sweet potatoes and spiced liquid can be prepared up to three days ahead and refrigerated. Bring each to room temperature before proceeding with the recipe. Each of these elements can also be frozen for up to three months; thaw overnight in the refrigerator before bringing to room temperature.