Preheat smoker to 350 degrees F using maple, cherry, or apple wood pellets, preferably. Spray a 9x13-inch disposable aluminum pan with cooking spray.
Dump cherry pie filling and crushed pineapple, including the juice, into the pan and stir together. Sprinkle the cake mix evenly over the top, then drizzle with the melted butter.
Bake for 45-60 minutes until top is golden brown and the filling is hot and bubbly.
Notes
This can also be made in the slow cooker by cooking on HIGH for 2 hours. It helps to place a couple paper towels between the lid and the dessert to absorb the excess condensation as the dump cake bakes.