1 tablespoon bourbon or 1 tablespoon whipping cream plus 1/2 teaspoon vanilla extract
2 tablespoons butter, softened
2 tablespoons dark brown sugar
2 tablespoons dark corn syrup
1/2 cup chopped pecans
Preheat oven to 400°. Place potatoes on a foil-lined baking sheet. Bake until tender, 40-50 minutes.
On a lightly floured surface, roll pastry dough to a 1/8-in.-thick circle; transfer to a 9-in. tart pan with removable bottom. Press onto bottom and sides of pan; trim edges to edge of pan. Refrigerate while preparing filling.
Remove potatoes from oven; increase oven setting to 425°. When potatoes are cool enough to handle, removepeel and place pulp in a large bowl; beat until smooth (you will need 1 cup mashed). Add butter, brown sugar, flour, pie spice and salt; beat until blended. Beat in egg, cream and bourbon. Pour into crust. Bake on a lower oven rack 15 minutes.
Meanwhile, for topping, mix butter, brown sugar and corn syrup until blended. Stir in pecans.
Remove pie; reduce oven setting to 350°. Spoon topping evenly over pie. Bake until a knife inserted near the center comes out clean, 8-10 minutes.
Cool on a wire rack. Serve within 2 hours or refrigerate, covered, and serve cold.