Preheat oven to 350 degrees F. Grease a 9x13 inch pan and set aside. Combine the cake mix, water, oil and eggs in a bowl. Mix and pour into prepared pan. Bake 350 degrees F for 34-38 minutes. When the cake is completely cool, crumble cake and set aside, reserving 1/4 cup of the crumbs for garnish.
In a medium mixing bowl, whisk milk, and pudding for 2 minutes until slightly thickened. Let sit 2 minutes or until softly set. Stir in pumpkin and spice. Mix well.
Clean and prepare your pumpkin with a large opening to create your bowl. If creating a carved pumpkin, tightly line the openings with plastic wrap to prevent spilling.
Layer 1/4 of the cake, 1/4 of the pudding and 1/4 of the whipped topping. Repeat until pumpkin is full, ending with the whipped topping. Garnish with the reserved crumbs.
NOTE: If using a large pumpkin as the serving vessel (similar to the one used in the recipe video) you may need to double or triple this recipe to fill your pumpkin completely.