Preheat oven to 180C. Mix butter and cake mix to a dough. Spread evenly in a paper lined rectangular baking dish and bake for 15 minutes.
Combine apple and sour cream. Spread evenly over base and return to oven for another 15minutes. C
Ool in the fridge. Serve cold.
Optional: You can sprinkle with cinnamon before the final bake or use a tin of pie apple with cinnamon instead.