1.Preheat oven to 350 degrees, spray an 8 or 9 inch square baking pan with cooking spray.
2.Spread apple pie filling in prepared pan. Top with dry cake mix, spread evenly. Top with thin slices of butter in single layer. Cover cake as best as possible.
3.In a small mixing bowl, mix together the oats, brown sugar, 2 tbsp cake mix, 2 tbps cinnamon and 2 tbsp soften butter. Use a fork or your fingers to get a crumbly mixture. Sprinkle over butter slices.
4.Bake approx. 45 to 60 minutes. Check after 45 minutes. Cake is done when wooden skewer or toothpick comes out clean or with dry crumbs.
5.Cool for about 15 to 20 minutes. Serve up and enjoy!