Preheat oven to 350.
Crust: Grease bottom only of a 13x9x2 inch pan. Reserving 1 cup dry cake mix, combine remainder with 1/2 cup melted butter (1 stick) and 1 egg with a pastry blender. Press into pan.
Filling: Combine filling mix with 2 eggs and 2/3 cup of milk. Pour over crust.
To use solid packed or fresh cooked pumpkin: Combine 1 lb. pumpkin, 2 1/2 tsp pumpkin pie spice (cinnamon, cloves, nutmeg), 1/2 cup firmly packed brown sugar, 2/3 cup milk, and 2 eggs. Pour over crust.
Topping: Combine 1 cup reserved cake mix, 1/4 cup sugar, 1 tsp. cinnamon, and 1/4 cup melted butter (1/2 stick). Mix together with a fork or pastry blender. Crumble and sprinkle over pumpkin filling.
Bake at 350 for 45-50 minutes. If desired, top with whipped cream.
Tip: Use your favorite simple yellow cake mix recipe to substitute for a boxed mix.