Preheat oven to 350 degrees F.
In a large mixing bowl, beat pumpkin pie mix, evaporated milk and eggs until well mixed.
Pour into greased 9 x 13 pan or two 8 x 8 pans.
Combine butter and cake mix. Use a fork or your fingers to make sure all the butter is incorporated into the cake mix.
Sprinkle the cake mix/butter mixture on top of the pumpkin mixture.
Bake for 15 minutes.
Remove from oven and sprinkle walnuts on top of cake mix.
Bake for 30 minutes longer.
The top should be a golden brown and your walnuts will be roasted.
Serve with whipped cream, ice cream, or brown sugar whipped topping.