Prepare the Oreo Crust: Crush 36 Oreo cookies into fine crumbs using a food processor or by placing them in a zip-top bag and crushing with a rolling pin. In a medium bowl, combine the crushed Oreos with melted butter until well mixed. Press the mixture evenly into the bottom of a 9×13-inch baking dish to form the crust.

Add the Ice Cream Layer: Allow the cookies and cream ice cream to soften at room temperature for about 10-15 minutes until spreadable but not melted. Spread the softened ice cream evenly over the Oreo crust. Cover the dish with plastic wrap or foil and freeze for at least 1 hour to firm up the ice cream layer.

Apply the Fudge Layer: Warm the hot fudge sauce slightly to make it pourable, but ensure it is not hot. Evenly drizzle the fudge sauce over the hardened ice cream layer, spreading gently if needed. Cover and return the dish to the freezer for an additional 1 hour.

Top with Whipped Topping: Once the fudge layer is set, spread the thawed whipped topping evenly over the top. Sprinkle additional crushed Oreo cookies over the whipped topping for garnish. Cover the dish and freeze for at least 2 more hours, or until the entire cake is firm.

Serve: Before serving, let the cake sit at room temperature for about 10-15 minutes to soften slightly for easier slicing. Cut into squares and enjoy this delectable treat!