1. Microwave chocolate and milk in 1 1/2 quart microwavable bowl on high for 2 minutes, stirring after 1 minute. Stir until chocolate is completely melted and smooth.
2. Stir in vanilla, salt and walnuts. Spread in greased 8 x 4 or 9 x 5 inch loaf pan. Refrigerate until firm, about 2 hours; cut into small squares.