Frost-on-the-Pumpkin Pie

1 (9-inch) graham cracker pie crust (purchased, or see recipe below)
1 can (16 oz.) vanilla frosting
1 can (15 oz.) canned pumpkin (NOT pumpkin pie mix)
1 cup sour cream
1-1/2 teaspoons ground cinnamon
1/2 teaspoon ground ginger
1/2 teaspoon ground cloves
1 cup whipped topping
2 tablespoons finely chopped nuts or graham cracker crumbs

Directions:
Combine frosting, pumpkin, sour cream, cinnamon, ginger, and cloves in a mixing bowl. Blend well. Gently fold in whipped topping. Pour mixture into pie crust and sprinkle with chopped nuts or graham cracker crumbs. Chill for 4 hours or more before serving.

Homemade Graham Cracker Crust

1-1/2 cups graham cracker crumbs
3 tablespoons sugar
1/4 teaspoon ground nutmeg
1/8 teaspoon ground cloves
1/3 cup margarine, melted

Directions:
Preheat oven to 350°. Blend all ingredients together to form a crumbly mixture. Save 1 tablespoon of mixture to use for topping. Press the rest of the mixture into a 9-inch pie dish. Bake 7-9 minutes or until lightly browned. Cool before using.