- 2 pounds sweet potatoes (about 4 medium)
- 1 2/3 cups half-and-half
- 1/2 cup sugar
- 2 large eggs
- 1 1/4 teaspoons cinnamon
- 1/4 teaspoon ground allspice
- 1/4 teaspoon freshly grated nutmeg
- 1/2 teaspoon salt
- pastry dough for a single-crust 9- to 10-inch pie
- 3 large egg whites
- 3/4 cup sugar
- confectioners' sugar for dusting
- Preheat oven to 400°F. and line a baking sheet with foil.
- Prick potatoes and bake on baking sheet in middle of oven 1 to 1 1/4 hours, or until very soft. Cool potatoes until they can be handled and scoop out enough flesh to measure 2 cups, reserving any remaining flesh for another use.
- In a blender or food processor purée potatoes with remaining filling ingredients until smooth. Filling may be made 1 day ahead and chilled, covered. Bring filling to room temperature before proceeding.
- On a lightly floured surface roll out dough into a 14-inch round (about 1/8 inch thick) and fit into a 9- to 10-inch (1-quart) glass pie plate, crimping edge decoratively. Chill shell 30 minutes
- Preheat oven to 375°F. with a baking sheet on middle rack.
- Pour filling into shell and bake on heated baking sheet in oven 1 hour, or until filling is set but center still shakes, slightly. (Filling will continue to set as pie cools.) Cool pie on a rack. Pie may be prepared up to this point 1 day ahead and chilled, covered loosely. Bring pie to room temperature before proceeding.
- Preheat oven to 450°F.
- In a metal bowl set over a saucepan of simmering water stir together whites and sugar until sugar is dissolved. Remove bowl from pan and with an electric mixer beat meringue on high speed until it holds stiff, glossy peaks.
- Transfer meringue to a pastry bag fitted with a large star tip and pipe tall pointed mounds close together, covering pie.
- Bake pie in middle of oven until meringue is golden brown, 4 to 5 minutes.
- Just before serving, dust pie lightly with confectioners' sugar. Serve warm or room temperature.