Mix the cookie crumbles and melted butter together and press them into the bottom of a 9x13 pan to form the crust. Then scoop the ice cream into the pan and press it down to form a layer. You may have to let the ice cream sit out for just a little bit so it's easier to press it into the pan, but you don't want it melted. Pour the fudge topping over the ice cream and then add a layer of cool whip on top of that. Break apart the remaining Oreos and just sprinkle them on the top. Cover with plastic wrap and place in the freezer for at lease 3 hours for it to set.