In heavy saucepan over low heat melt chocolate chips, milk & margarine. Remove from heat and in large bowl combine nuts & marshmallows, pour over them the chocolate mixture and mix well. Spread in waxed paper lined 13x9 in pan & chill 2 hrs. Remove from pan and peel off wax paper, cut in squares. This mixture can also be dropped by spoonfuls on waxed paper lined cookie sheets.