3 cups granulated sugar1 can (12 ounces) evaporated milk¼ cup (½ stick) butter or margarine½ teaspoon salt4 cups miniature marshmallows4 cups (24 ounces) chocolate chips1 cup chopped pecans or walnuts (optional)2 teaspoons vanilla extractLine one 13 x 9-inch baking pan or two 8-inch-square baking pans with foil.Combine sugar, evaporated milk, butter and salt in a 4- to 5-quart heavy-duty saucepan. Bring to a full rolling boil over medium heat, stirring constantly. Boil, stirring constantly, for 4 to 5 minutes. Remove from heat.Stir in marshmallows, morsels, nuts and vanilla extract. Stir vigorously for 1 minute or until marshmallows are melted. Pour into prepared pan(s).Refrigerate for 2 hours or until firm. Lift from pan and remove foil. Cut into pieces.Store tightly covered in refrigerator.