Dark Chocolate Pistachio Fudge

In large saucepan, melt dark chocolate chips over low heat with condensed milk and salt. Remove from heat and stir in pistachios and vanilla. Spread evenly onto a waxed paper-lined 9-inch square pan. Chill for at least 2 hours. Turn fudge over onto cutting board, peel of waxed paper and cut into squares. Store covered in refrigerator.