Apple Crisp using Yellow Cake Mix

I think I learned this recipe from a Pampered Chef party and I modified it to be gf. spray a 8x11 cake pan with Pam spray or similar. Add 5 peeled and cut up apples. In a separate bowl, mix the gf yellow cake mix and 1 stick melted butter. I usually get King Arthur yellow cake mix. Add 2 tablespoons of cinnamon or 1/2 cup brown sugar or 1/2 cup regular sugar if desired. I don’t add cinnamon or sugar, but did when I had a bigger sweet tooth. Bake for 30 minutes on 375 degreea in the oven. Serve warm with vanilla ice cream if desired.