Preheat oven to 400 degrees. Pour pie filling into a greased pie plate or into a seasoned cast iron skillet/pot. Mix the dry ingredients together well. Melt 1/4 cup (1/2 stick) of butter and pour over dry ingredients. Mix well. It will be crumbly. Spread this over the top of the pie filling. Bake for 20 minutes. Let sit for at least 5 minutes before serving.