Preheat oven to 375 degrees F. Grease a 9x13 inch baking pan with cooking spray.
Mix together the dry cake mix and oats. Add melted butter and mix until combined and crumbly. Press ⅔ of the mixture into prepared pan.
Spread apple filling over crust in a single layer. Sprinkle the remaining crumb mixture over filling.
Bake for 25 minutes. Carefully remove from oven. Allow bars to cool for 15 minutes or more, before cutting into bars. Serve and enjoy!