Spray a 9x13x3-inch pan with non-stick cooking spray on the bottom and lightly on the sides. It’s very important to use a dish that is 3 inches deep because it creates space for the graham crackers to be snug up against all of the edges.
Mix pudding and milk using either a mixer with a whisk attachment or a mixing bowl and a whisk.
Fold in the Cool Whip until it is fully incorporated and there are no more white and yellow swirls. You want the mix to be fully yellow and uniform.
Layer graham crackers along the bottom of the pan covering the entire bottom to the edges.
Divide the pudding mixture in half.
Spread the first half of the pudding mixture on top of the first graham cracker layer ( an offset spatula is great for this) until fully covered. Do your best to get each layer as level as possible so your end product is evenly distributed.
Spread the second layer of graham crackers on top of the pudding layer to the edges.
Fully spread the remaining pudding mixture over the second layer of graham crackers.
Lay the third and final layer of graham crackers to the edges.
Microwave your tub of dark chocolate fudge frosting (DO NOT microwave the frosting in the tub, move to a microwave safe bowl) for 30 seconds, remove and stir fully.
Microwave for another 30 seconds, stir and remove any lumps. Immediately pour the frosting onto the final layer of graham crackers and spread gently to the edges. With two hands give your whole dish a gentle shake back and forth for a few seconds to level out your layers!
Cover in saran wrap and chill in the refrigerator for 10 hours or overnight.
When you’re ready to serve your cake, remove it from the fridge and let the cake thaw uncovered for 15 to 20 minutes for it to get that beautiful shine restored to the frosting topping.