Preheat the oven to 350 degrees F. Spray a 12-inch cast iron skillet or 9 x 13 cake pan with nonstick spray.
Fill the skillet with the frozen peaches spreading them evenly. Top with the DRY cake mix.
Covering the cake mix as much as possible, pour the soda over evenly. (Don't mix soda and cake mix so you get the crumbly topping instead of cake topping!)
Bake for 45-55 minutes or until the a toothpick inserted to the cake comes out clean.