sweet potato pie is not a substitute for pumpkin...it should have its own distinct flavor profile...to me, that means mace and cardamom...
2 1/2 cups all-purpose flour
1 teaspoon coarse salt
1 teaspoon sugar
1 cup (2 sticks) chilled unsalted butter, cut into pieces
1/4 to 1/2 cup ice water
Place the flour, salt, and sugar in the bowl of a food processor, and process for a few seconds to combine. Add the butter pieces to the flour mixture, and process until the mixture resembles coarse meal, about 10 seconds. Add the ice water in a slow, steady stream, pouring it through the feed tube with the machine running, just until the dough holds together. Do not process for more than 30 seconds.
Turn the dough out onto a work surface. Divide into 2 equal pieces, and place on 2 separate sheets of plastic wrap. Flatten, and form 2 disks. Wrap, and refrigerate at least 1 hour before using.
1/2 cup (1 stick) butter, cut into pieces, room temperature
1 1/4 cups granulated sugar
2 large eggs
1/2 teaspoon ground cardamom
1 teaspoon ground mace
1/4 teaspoon freshly ground nutmeg
1 teaspoon pure vanilla extract
1 cup of heavy cream
On a lightly floured work surface, roll pate brisee into a 15-inch round. With a dry pastry brush, sweep off the excess flour; fit dough into a 9-inch pie plate, pressing it into the edges. Trim to a 1-inch overhang all around. Crimp edge as desired. Cover with plastic wrap; chill pie shell until firm, about 30 minutes.
Preheat oven to 375 degrees. Fill a medium saucepan with 2 inches of water; place over high heat and bring to a boil. Fit saucepan with a steamer basket, add sweet potatoes, and cover. Steam until potatoes are easily pierced with a fork, about 1 hour. You may need to add more water as sweet potatoes steam. Let sweet potatoes cool slightly before removing skins by rubbing potatoes with a paper towel.
Place sweet potatoes in a bowl and mash with a hand potato masher or fork. the potato should hold some of their texture and form (once again, this is not a pumpkin pie)
Add butter and beat by hand until well combined and cooled slightly. Slowly add sugar. Add eggs, one at a time, beating after each addition. Add cardamom, mace, nutmeg, vanilla, and heavy cream. Continue beating until well combined, but not mush. once the butter and eggs are well-combined you can fold the remaining ingredients into the mix.
Pour mixture into prepared pie crust. Transfer to oven and bake until center has set, 45 to 50 minutes.