Pour the stick of melted butter over the cake mix. Preheat oven to 400. https://www.cornbreadmillionaire.com/Therecipe/lemon-pineapple-dump-cake Pour the 2 can of lemon pie filling in the bottom of a 9*13 cake pan or baking dish that has been greased with cooking spray. https://www.tasteofhome.com/recipes/pineapple-upside-down-dump-cake Pour the dry cake mix over the pie filling, spreading it evenly. Spread the pie filling in the bottom of the baking dish. Preheat the oven to 325ºF. How to Make Lemon Dump Cake. Spray a 9×13-inch baking dish with nonstick cooking spray. Instructions.