Preheat oven to 425°. On a lightly floured surface, roll dough to a 1/8-in.-thick circle; transfer to a 9-in. pie plate. Trim crust to 1/2 in. beyond rim of plate; flute edge. Refrigerate while preparing filling.
In a bowl, blend sugar and spices. Beat eggs; add milk and vanilla. Combine the sugar mixture. Stir in potatoes; beat until smooth. Pour into pie crust. Bake for 15 minutes. Reduce heat to 350° and bake for an additional 30 minutes. Combine topping ingredients. Remove pie from the oven; sprinkle with topping. Bake until topping is golden brown, 10-15 minutes. Cool on wire rack. Store in the refrigerator. Serve with whipped topping or ice cream.
Dough for single-crust pie: Combine 1-1/4 cups all-purpose flour and 1/4 tsp. salt; cut in 1/2 cup cold butter until crumbly. Gradually add 3-5 Tbsp. ice water, tossing with a fork until dough holds together when pressed. Shape into a disk; wrap and refrigerate 1 hour.