1 Box Pillsbury Sugar Free Yellow Cake Mix
2 16 oz packages frozen blackberries
1 16 oz bottle of Diet Sprite
Preheat oven to 350. Lightly spray a 9x13 pan with cooking spray.Put the frozen blackberries in the pan. Before opening the package, knead the lumps out of the dry cake mix , then spread over the berries. Pour the Diet Sprite over top of the cake mix covering well. Bake for 30-40 minutes until golden brown. Serve with sugar free whipped topping or ice cream if desired.