Spray inside of glass or ceramic 9x13 casserole dish with nonstick cooking spray, and set aside.
Empty can of Cherry Pie Filling and drained can of Crushed Pineapple into mixing bowl, and stir well.
Pour Cherry-Pineapple mixture into bottom of baking dish, and spread evenly.
In a medium mixing bowl, combine dry Butter Yellow Cake Mix and melted Butter, and stir until crumbly. (break up large chunks into small crumbles using a spoon)
Pour butter/cake crumble mixture over the Cherry-Pineapple layer in the baking dish.
Bake for 30 minutes, or until sides are hot and bubbly.
Serve up with some Whip Cream or a scoop of Vanilla Ice Cream and enjoy!