Baking the pie on the bottom rack creates a crisp crust. If you can't find cane syrup, substitute ¼ cup light corn syrup and ¼ cup molasses.
1 cup all-purpose flour
¼ cup self-rising soft-wheat flour
¼ teaspoon salt
½ cup cold unsalted butter, cut into ¼-inch pieces
5 tablespoons ice water
3 large eggs, separated
2 cups baked, peeled, and mashed sweet potato (about 2 large)
1/3 cup heavy cream
½ cup cane syrup
¼ teaspoon salt
1 teaspoon vanilla extract
½ teaspoon grated lemon peel
1 cup cold heavy cream
2 tablespoons powdered sugar
½ teaspoon vanilla extract
Whisk together first 3 ingredients in a medium bowl until blended. Cut in butter with a pastry blender until crumbles are about the size of small peas. Sprinkle ice water, 1 tablespoon at a time, evenly over surface of mixture in bowl; stir with a fork until dry ingredients are moistened. Shape into a ball. Roll out pastry to an 11-inch circle. Fit pastry into a 9-inch pie plate; fold edges under and crimp. Place pastry in refrigerator while preparing filling.
In a medium bowl, beat egg whites at high speed with an electric mixer until soft peaks form. Place sweet potato in a large bowl. Beat with a mixer at medium speed until smooth. Add egg yolks, 1/3 cup cream, and next 3 ingredients, beating until smooth. Stir in lemon peel. Fold about one-third of the beaten egg whites into potato mixture. Fold in remaining egg whites. Pour filling into prepared crust.
Bake at 375° on bottom rack 40 minutes or until set. Let cool completely on a wire rack.
While pie cools, beat 1 cup cream, powdered sugar, and vanilla in a chilled bowl until soft peaks form. Serve pie with whipped cream. Makes 1 (9-inch) pie.