Preheat oven to 375 degrees F. Spray a 9 by 13-inch casserole dish with butter flavored cooking spray.
Spread half of the apple pie filling in the bottom of the casserole dish. Sprinkle with the cinnamon and 1 1/2 packets of oatmeal. Dot with half the butter. Repeat with remaining ingredients.
Cover with foil and bake for about 1 hour. Remove from oven and let sit for 5 minutes before serving.