Heat oven to 350°F. Spray bottom of 13x9-inch (3-quart) glass baking dish or 3-quart casserole with cooking spray.
Spread pie filling in baking dish.
Top with dry cake mix; gently shake pan to distribute evenly.
Pour melted butter over the dry cake mix, tilting pan to cover as much of the top with butter as possible.
Bake 42 to 45 minutes or until mostly dry on top and bubbly around edges. Cool 45 minutes before serving. Serve warm with whipped topping or ice cream. Store loosely covered in refrigerator.
