*This makes a dessert about an inch thick or less. That's because I like a high topping-to-pumpkin ratio. If you'd like it thicker, use a large can of pumpkin and double the rest of the filling ingredients (Eggs, sweetened condensed milk, and spices). Leave the rest of the recipe the same. Preheat oven to 350. Place 2 C of the cake mix in a bowl. Cut in 3 T chilled butter. Just use your fingers to crumble the butter until it's in small crumbly pieces. Place mixture in a 9x13 baking dish and press flat with your fingers. Mix pumpkin, eggs, sweetened condensed milk, and spices until smooth. Pour on top of the cake mixture in the pan.
Now take 1 C of remaining cake mix and mix in 1/2 t cinnamon. Sprinkle it all over the top of the pumpkin mixture.
Drizzle 3 T of melted butter on top.
Pop it in your 350 degree oven for about 40 minutes or so. A knife should come out clean and topping should be nice and golden.