Preheat oven to 350 degrees F. Spray a 13"x9" baking dish with cooking spray.
Layer pineapple (with the juice), then cherry pie filling in the baking dish. Sprinkle with chocolate cake mix, then arrange butter slices evenly over the top.
Bake in the 350 degree oven for 50 minutes, or until fruit is bubbly is chocolate cake is cooked through and golden.
Allow to cool slightly before serving. I recommend topping with a big scoop of vanilla ice cream.
This Cherry Dump Cake should be refrigerated for up to 3 days, and frozen for up to 3 months. It can be served chilled right out of the fridge or warmed slightly in the microwave and topped with ice cream or whipped cream.