Prep the pan: Line a 9x13-inch baking dish with a thin layer of graham crackers. Break pieces as needed to fully cover the bottom with minimal gaps.
Mix the pudding: In a large bowl, whisk instant pudding with cold milk and vanilla for about 2 minutes until thick.
Let it sit for another 2–3 minutes to fully set.
Fold in the whipped topping: Gently fold the whipped topping into the pudding until smooth and fluffy. Don’t overmix—keep it light.
First filling layer: Spread half of the pudding mixture evenly over the graham crackers. Smooth the top with a spatula.
Second cracker layer: Add another even layer of graham crackers over the filling, again fitting pieces to cover the surface.
Second filling layer: Spread the remaining pudding mixture on top.
Level the surface for clean slices later.
Final cracker layer: Finish with one more layer of graham crackers. Press gently so they adhere, but don’t crush them.
Make the chocolate topping: Heat the cream in a small saucepan until steaming (not boiling). Remove from heat, add chocolate chips, butter, and a pinch of salt.
Let sit 2 minutes, then whisk until glossy and smooth.
Top the cake: Pour the warm chocolate over the crackers. Tilt the pan to cover edge to edge. If needed, use an offset spatula to smooth.
Chill: Cover and refrigerate for at least 6 hours. Overnight is best so the crackers soften into a cake-like texture.
Serve: Slice with a sharp knife.
Wipe the blade between cuts for clean layers. Add optional garnishes right before serving.