Foolproof Dark Chocolate Fudge

3 C semisweet chocolate chips 1 can (14 oz.) sweetened condensed milk dash salt 1 C chopped walnuts 1 1/2 tsp. vanilla
In heavy saucepan over low heat, melt chips with sweetened condensed milk and salt. Remove from heat; stir in walnuts and vanilla. Spread evenly into aluminum foil lined 8 or 9 inch square pan. Chill 2 hours or until firm. Turn fudge onto cutting board; peel off foil and cut into squares. Store loosely covered at room temperature.