Place half of the ice cream sandwiches into the pan. Note: I find that placing 6 on one side and then trimming the other 6 to fit the other side works best, but you can do whatever you'd like as long as the bottom is covered with ice cream sandwiches.
Spread with half of the whipped topping.
Sprinkle with half of the crushed Oreo cookies.
Place the remaining ice cream sandwiches on top, in the same manner as the bottom layer.
Spread with the remaining whipped topping.
Sprinkle with remaining crushed cookies.
Freeze for 2-3 hours before serving.
Video
Notes
If serving the next day, freeze for 2 hours, then cover with plastic wrap.Note: If you cover it with plastic wrap before freezing, the whipped topping will stick to the plastic. It's best to freeze the cake first, then cover.