Mix the Filling: In a large mixing bowl, whisk together the instant vanilla pudding mix and the cold milk until it begins to thicken (about 2 minutes). Gently fold in the thawed whipped topping with a rubber spatula until smooth and combined.

First Layer: In an ungreased 9x13-inch baking dish, arrange a single layer of graham crackers across the bottom. Break pieces as necessary to fit the edges.

Layer the Cream: Spread exactly half of the pudding mixture evenly over the graham crackers.

Repeat: Top the pudding with a second layer of graham crackers. Spread the remaining half of the pudding mixture evenly over the top.

Final Crackers & Quick Chill: Place a third and final layer of graham crackers over the pudding. Cover the dish with plastic wrap and refrigerate for 30 to 60 minutes to allow the top layer to set up.

Prepare the Glaze: Remove the lid and the foil seal from the tub of chocolate frosting. Microwave for 15 seconds to soften it. Stir well until the frosting is glossy and easily spreadable.

Frost the Cake: Remove the cake from the fridge, take off the plastic wrap, and pour the softened frosting over the top. Spread it out evenly to the edges.

Chill Overnight: Cover the dish tightly again with plastic wrap (ensuring it doesn't touch the frosting) and refrigerate overnight, or for at least 8 hours. The crackers must have time to absorb the moisture and soften into a cake-like texture.

Serve: Slice into squares and serve chilled!