Begin the recipe by preheating the oven to 350 degrees F. and grab a 9x13-inch rectangle or 11x11-inch square baking dish. Pour two 21 ounce cans of apple pie filling into the bottom of the dish and spread evenly.
Top with the entire box of yellow cake mix and evenly spread it on top of the apple pie filling.
Top with thin ½ cup slices of butter and spread out evenly on top of the yellow cake mix.
Place into the oven and bake for 45 to 50 minutes, until the top has lightly browned and the apple filling is warm and bubbly. Carefully remove the 3 ingredient apple dump cake from the oven and serve warm. Enjoy!
Cover and place any leftovers in the refrigerator for up to 4 days.