Pulse the 36 chocolate sandwich cookies to fine crumbs, mix with the 6 tbsp melted butter until the crumbs clump like wet sand, press firmly into a 9x13-inch dish, and refrigerate.

Beat the 8 oz cream cheese, 1/4 cup sugar, and 2 tbsp milk on medium speed for 2 minutes until smooth, fold in 1 1/4 cups whipped topping, spread over the crust, and return to the fridge.

Whisk both packages of pudding mix into the 3 1/4 cups milk for 2 minutes until thick, spread immediately over the cream cheese layer, and refrigerate for 5 minutes.

Spread the remaining whipped topping over the pudding layer, cover loosely with plastic wrap, and refrigerate for at least 4 hours or overnight.

Shave the 1 1/2 oz dark chocolate over the top, slice into 12 squares with a clean blade, and serve straight from the fridge.