Preheat oven to 350 degrees.
Add pie filling to baking dish and spread into an even layer that covers the bottom of the dish.
Sprinkle entire box of cake mix over the pie filling.
Place pats of butter on top of the cake mix, covering as evenly and as much of the cake as possible.
Bake for 40 minutes. Test for doneness by inserting a toothpick into the center of the cake. It should come out clean (though the tip may have some pie filling on it).
Serve warm. Tastes best warm or at room temperature but leftovers may be stored in the refrigerator for 3-4 days.
Notes: You can easily reduce the sugar in this recipe by using sugar-free apple pie filling instead. You can also replace the golden butter cake mix with yellow cake mix or vanilla cake mix.