I got this recipe years ago as a sophomore in college from my roommate Sarah Nelson. I have loved it ever since.
1 yellow cake mix (reserve 1 cup for topping)
1/2 cup melted butter
Mix above ingredients and pat into 9/13 pan. Mixture will be sticky
1/2 can pumpkin filling (or just one smaller can)
3/4 cup evaporated milk
1 cup sugar
3 tsp pumpkin pie spice (or you can mix together 1/2 tsp. cinnamon, 1/2 tsp. nutmeg, 1/2 tsp. cloves, and 1/2 tsp. ginger and use in the place of the pumpkin pie spice).
Mix the above ingredients and pour over cake mix.
1 cup cake mix (reserved from earlier)
1/3 cup soft butter
1 tsp cinnamon
1/2 cup brown sugar
1/2 cup chopped nuts (but I never do)
Sprinkle above ingredients on top of pumpkin mixture and bake at 350 degrees for 45-55 minutes. Serve with Cool whip, whip cream, or ice cream. I have loved it with all of them!