Add all ingredients in mixer (except water, 1/4 of pudding mix and whipped cream). Mix on low. Add in water gradually. It will be a little thick. Stop half way and stir the bottom and sides to make sure all dry ingredients are incorporated well.
Spray a 9x13x2" baking dish with no stick cooking spray. Spread the batter in evenly.
Bake as directed on box (may be a few extra) check before taking out. Let cool.
In a sealable plastic bowl, whisk the whipped topping and remaining pudding mix. Cover and refrigerate for at least one hour.
Cut cake in six slices, each piece cut in half. Put one Tbsp. of the whipped topping, cover with the other half, dollop another Tbsp. on the top.