1/2 recipe Pie Crust, see recipe below or store-bought
2-1/4 pounds orange-fleshed sweet potatoes, such as Garnet (sometimes called "yams")
3 large eggs
2/3 cup packed light brown sugar
1/3 cup granulated sugar
3 tablespoons pareve whipping cream
3 tablespoons melted margarine
2 1/2 teaspoons vanilla extract
3/4 teaspoon cinnamon
1/2 teaspoon kosher salt
1/4 teaspoon ground allspice
1/4 teaspoon nutmeg
2 tablespoons packed light brown sugar
1 tablespoon dark corn syrup
1 tablespoon melted margarine
1 teaspoon vanilla extract
1/4 teaspoon kosher salt
1/4 teaspoon cinnamon
1/2 cup coarsely chopped pecans
Make pastry as directed in a regular 9-in. pie pan. Let cool.
Preheat oven to 375° and make filling: Bake sweet potatoes in a shallow pan until very tender when pierced, 1 1/4 to 1 3/4 hours. Let cool. Scoop flesh into a food processor and purée until smooth. Measure 2 cups; save extra for soup or another use.
Reduce oven to 350°. With a mixer, beat eggs in a large bowl until frothy. Beat in remaining filling ingredients until blended. Pour into crust and spread level. Wrap pie rim with 4 strips of foil.
Bake pie 30 minutes. Meanwhile, in a small bowl, stir together topping ingredients except pecans until smooth. Stir in pecans.
Remove foil from pie. Evenly drop small spoonfuls of pecan mixture in a border around edge of pie. Continue to bake until center jiggles only slightly when shaken gently, 15 to 20 minutes. Let cool on a rack at least 2 hours.
Make ahead: Through step 2 or the whole pie, up to 1 day.
2 1/2 cups flour
1 1/2 tablespoons sugar
1 teaspoon kosher salt
4 tablespoons cold vegetable shortening
10 tablespoon cold unsalted margarine, cut into 1/2-in. cubes
In a mixer, beat flour, sugar, and salt on low speed to blend. Add shortening in spoonfuls and beat on low speed until pieces are pea-size, about 1 minute. Add margarine and beat until pieces are pea-size, stopping once to scrape bowl, about 2 1/2 minutes. Gradually drizzle in 5 1/2 tbsp. ice water, beating just until dough comes together, 15 to 30 seconds.
Divide mixture in half and gently gather and press each into a 3/4-in.-thick disk. Wrap each in plastic wrap. Chill until firm, at least 2 hours and up to 2 days.
Unwrap 1 pastry disk and lightly flour pastry, work surface, and rolling pin (save remaining disk for another use). Working from center with short strokes, roll pastry into an even 12-in. circle. As you work, lift pastry using a bench scraper or long metal spatula, and reflour board and pin as needed to keep it from sticking.
Fold pastry in half and open up into a regular 9-in. pie pan, easing it into place without stretching. Using scissors, trim overhang to 1 in.
Roll overhang under itself so it's flush with and sitting on top of rim. Pinch pastry along lip to form an even ridge. Flute ridge. Wrap with plastic wrap and freeze until firm, 30 to 40 minutes.
Preheat oven to 400° with a rack in lower third. Line pastry with foil, letting ends come straight up from pan but not over rim. Fill with pie weights or dried beans. Bake until crust is golden at edges, 20 to 25 minutes. Remove foil and weights. If needed, bake until center is dry, 2 to 5 more minutes.
Make ahead: For dough, up to 2 days, chilled or 1 month, frozen. For blind-baked crust, up to 1 day, airtight.