Preheat oven to 350 degrees and prepare a 13x9 pan with nonstick spray
Spread pumpkin in pan
Sprinkle on pumpkin pie spice
Microwave frosting for about 30 seconds and pour over pumpkin
Sprinkle on walnuts then evenly add the cake mix
Place butter slices on top
Bake for 40-45 minutes
Cool completely and serve
