Place the crush cookies in a 9×13 inch pan. Add the 1/2 cup of melted margarine and toss with a fork until mixed well.
Spread out the cookie mixture in the bottom of the pan and place in freezer until frozen solid (about 1 hour). While the cookie crust is freezing, set the chocolate ice cream out to start thawing so it is easy to spread over the cookie crust.
Spread the entire carton of chocolate ice cream over cookie crust and place in the freezer until frozen (about one hour).
Next spread the 8 oz. container of Cool Whip over the frozen chocolate ice cream and place in freezer again for about an hour. Then spread the fudge over the frozen Cool Whip layer.
Happy birthday Jon!