Preheat oven to 375 degrees F. Prepare pastry as directed; line a 9-inch pie plate with the pastry circle. Trim to 1/2 inch beyond edge of pie plate. Fold under extra pastry and flute or crimp edge. Do not prick pastry. Set aside.
For filling, in a large bowl, stir together pumpkin, sugar, flour, and cinnamon. Add eggs and vanilla; beat lightly with a rotary beater or fork just until combined. Gradually stir in half-and-half or light cream.
Place pastry-lined pie plate on the oven rack. Carefully pour filling into pastry shell. Sprinkle chopped candy over filling.
To prevent overbrowning, cover pie edge with foil. Bake for 25 minutes. Remove foil. Bake for 20 to 25 minutes more or until a knife inserted near the center comes out clean (some chocolate from the candies may adhere to the knife but no pumpkin should). Cool on a wire rack for 1 hour. Cover and chill for at least 3 hours or up to 24 hours. Makes 8 servings.
Pastry for Single-Crust Pie
Stir together flour and salt. Using a pastry blender cut in shortening until pieces are pea-size. Sprinkle 1 tablespoon of the water over part of the mixture; gently toss with a fork. Push moistened dough to side of the bowl. Repeat moistening dough, using 1 tablespoon of the water at a time, until all the dough is moistened. Form dough into a ball. On a lightly floured surface, use your hands to slightly flatten dough. Roll dough from center to edge into a circle about 12 inches in diameter.