Preheat oven to 400 degrees F. Line a 15x10-inch baking pan with foil. Prepare Pastry for a Double-Crust Pie. Pat onto bottom and up sides of prepared pan. Do not prick pastry. Line pastry with a double thickness of foil. Bake 10 minutes; remove foil.
Meanwhile, in a large bowl combine next four ingredients (through salt). Stir in eggs just until combined. Gradually stir in half-and-half. Spread over partially baked piecrust.
Bake 30 minutes more or until a knife comes out clean. Cool on a wire rack. Cover and chill within 2 hours. If desired, serve with whipped cream and sprinkle with additional pumpkin pie spice.
Pastry for a Double-Crust Pie
In a large bowl stir together flour and salt. Using a pastry blender, cut in shortening and butter until pieces are pea size. Sprinkle 1 tablespoon of the ice water over part of the flour mixture; toss gently with a fork. Push moistened pastry to the side of the bowl. Repeat moistening flour mixture, using 1 tablespoon of the ice water at a time, until all of the flour mixture is moistened. Gather flour mixture into a ball, kneading gently until it holds together. Divide pastry in half; form halves into balls.