1Mix crushed cookies and melted margarine together and pat into the bottom of a 13 x 9 inch dish. Refrigerate for 1 hour.
2Slowly melt chocolate chips and remaining stick of margarine. Gradually add milk and sugar; stirring constantly until mixture comes to a boil. Boil 8 minutes. Remove from heat and add vanilla.
3Spread softened ice cream over chilled crust. Pour hot mixture over ice cream. Spread whipped topping and sprinkle with nuts. Freeze. Take out of freezer a bit before serving so that you can cut it easily.