Unwrap ice cream, slice in about 8 slices. Put on top of crust.
For Fudge, boil powdered sugar, evaporated milk, chocolate chips and butter for 8 minutes. Remove from heat and cool. When cool add vanilla.
Make fudge the day before. Sprinkle chopped walnuts over ice cream. Spread fudge on. Add Cool Whip. Sprinkle reserved Oreo cookies on top. Then freeze.