FOR THE FILLING: Place the hot fudge topping in a microwave-safe bowl on high in 10-second intervals until warm (not hot).
Add 1 cup Cool Whip and stir to combine. Add the pudding mix and stir vigorously until thoroughly combined, 1 to2 minutes. Fold in half of the chopped cookies.
On a long sheet of nonstick heavy-duty aluminum foil, place 4 of the ice cream sandwiches side by side. Layer about half of the filling on top of the sandwiches. Layer 4 more ice cream sandwiches on top of the filling, and then top with remaining filling. Top with the last 4 ice cream sandwiches.
Ice the cake on the sides and top with remaining Cool Whip. Scatter the sprinkles and remaining cookie crumbles over the top. Freeze overnight. Freeze any leftovers.