Crush 25 of the Oreo cookies. I used a blender, but you can place the cookies in a zip-lock bag and smash them with a hammer/mallet also.
Melt the butter and combine with the Oreo crumbs.
Press crumbs into the bottom of your pan to form crust.
In a separate bowl, mix the ice cream with the whipped topping. It helps to have the ice cream sit out for about 20 minutes beforehand.
Scoop the mixture over the crust and freeze until ready to serve.