Prep the dish: Lightly grease a 9x13-inch baking dish or line it with parchment. This helps slices lift out cleanly.

Mix the pudding: In a large bowl, whisk instant pudding with cold milk for about 2 minutes until thick. Fold in the whipped topping gently until smooth. Stir in vanilla and a tiny pinch of salt if you like.

First cracker layer: Arrange a single layer of graham crackers on the bottom of the dish. Break pieces to fit snugly with minimal gaps.

Spread the filling: Spoon half the pudding mixture over the crackers. Smooth it to the edges with an offset spatula or the back of a spoon.

Second cracker layer: Add another full layer of graham crackers on top of the filling.

More filling: Spread the remaining pudding mixture evenly over that second cracker layer.

Final cracker layer: Top with a third, even layer of graham crackers. Press lightly to even everything out.

Add the chocolate: If using tub frosting: Remove the lid and foil, microwave 20–30 seconds until pourable but not hot. Stir well, then pour over the crackers. Spread to the edges.

If making ganache: Heat cream until steaming, pour over chocolate chips, let sit 2–3 minutes, add corn syrup if using, then stir until glossy. Cool 5 minutes and pour over the cake. Spread evenly.

Chill: Cover and refrigerate at least 6 hours, ideally overnight. The crackers soften into “pastry” and the flavors meld.

Serve: Slice with a sharp knife. For clean edges, wipe the knife between cuts. Keep leftovers chilled.