1. In heavy saucepan, over low heat, melt chocolate chips with condensed milk and margarine. Remove from heat.
2. In large bowl – combine nuts and marshmallows – fold in chocolate mixture.
3. Spread in wax paper lined 13 x 9 inch pan.
4. Chill at least 2 hours. Remove from pan and peel off wax paper.
5. Cut into squares – store covered at room temperature (won't last long anyways) or freeze in waxed paper.