In a large bowl, whisk 2 boxes of instant pudding with the 4 cups of milk. Mix until it starts to become soft-set (3-5 minutes).
In a 9x13 dish, place down parchment paper that overhangs on both sides if you want to pull it out later. Start by spreading about 2 tbsp on the bottom (this helps the crackers stay in place a little more). Layer the whole bottom with the graham crackers and top with only enough pudding so that you don’t see the crackers anymore. Don’t make it too thick.
Continue layering until you reach the top of the dish, ending with chocolate pudding. Top with all of the whipped cream. Sprinkle graham cracker crumbles or cocoa powder on top.
Put in the refrigerator and let chill for at least 8 hours