Prepare cake in 9 x13 pan according to directions on box. When golden remove from oven an let cool for a few minutes.
When just slightly cooled, use the handle end of a wooden spoon into the baked cake. Don't be shy; make the holes big enough for the pudding to seep into and go deep enough with the spoon that you hit the bottom of the pan.
Next, prepare pudding mixture combine 4 cups of milk an pudding mix; whisk until fully combined and there are no lumps.
pour pudding mixture over entire cake before it starts to get thick. Spread evenly filling all holes.
Refrig for 2 hours or till set.
Topped with sliced banana, whipped topping an crushed vanilla wafers