In 2 qt. Glass measure, combine marshmallows, milk, and salt. Microcook on High 3-4 minutes. Stir until marshmallows melt and mixture is smooth. Add chips and stir until melted. Stir in nuts (may use up to 1 cup) and vanilla.
Line 8 or 9 inch square pan with wax paper. Spread fudge evenly in pan. Chill 2 hours, until firm. Turn on to cutting board, peel off paper and cut into squares.
