Two 12-oz bags frozen mixed berries
1 box white cake mix (no pudding)
1 can of diet 7-up or sierra mist (clear soda)
Place frozen fruit in a 9x13 baking dish. Add dry cake mix over the top. Pour soda slowly over cake mix. DO NOT stir the cake mix and the pop - this will give you a 'crust'. If you stir the two, you will have a cake like topping.
Bake 350 for 45-50 min.
You may be able to use frozen peaches instead of mixed berries