Prepare cake mix according to instructions on the box for 9 X 13 cake pan. Once cake is baked and remove from oven, allow cake to cool, 10 mins. Then with a spoon handle, preferable a wooden spoon, began poking small holes throughout the cake.
Prepare Chocolate sauce while cake bakes.
Melt butter in a sauce pan and add cocoa. Combine it and then remove from heat. Add milk, vanilla and powder sugar. stir to combine. After holes are poked in cake, pour sauce of over warm cake
In a bowl prepare the pudding. Whisk together the instant pudding mix with 4 cups of milk. Stir until all lumps dissolve, let pudding sit for about 2 mins to thicken up but not completely set. it should be easy to pour.
Pour pudding over cake with chocolate sauce layered. Make sure pudding completely covers cake. Refrigerate cake over night. You may want to crush your vanilla wafers now. Put wafers in a plastic ziploc and crush gently with wooden spoon.
Next morning, spread whipped generously over cake leaving about 4 oz of cream for final topping. Grab a pyrex glass dessert bowl. Carefully spoon cake out of cake pan keeping layers in place, transfer from pan to bowl. Fill bowl at least 3/4 high. This will look like a mess but keep spooning. Once bowl is filled, topped dessert with the remaining whip cream. Spread crush vanilla wafers over the top of whip cream and refrigerate until ready to serve.