Preheat oven to 350F degrees. Spray a 9x13-inch baking dish with nonstick cooking spray.
Prepare cake mix according to package directions.
Pour prepared cake batter into baking dish.
In a separate bowl, combine dry pudding mixes with sugar, milk and water.
Whisk briskly for 2 minutes until it begins to thicken.
Spoon pudding mixture over cake mix batter. Once it is on there, it is hard to spread out since it kind just ends up sinking into the batter.
Put a large baking sheet underneath your baking dish before sliding it in the oven.
Bake for about 55 minutes to one hour.
It's a bit tricky to tell when it is done because the pudding layer in it always stays a bit jiggly. So, what you want to do is take a toothpick and insert it into the middle of the cake. If it only comes out with pudding - you are good. If you still see gooey cake batter on it, then you need to bake it for a bit longer.
When it’s finished baking, allow it to cool for about 20 minutes. This will allow that pudding layer to thicken up a bit more.
Then serve with a bit of sprinkled powdered sugar on top.