Line 8 inch-square pan with foil. Combine sugar, evaporated milk, butter and salt in a medium, heavy-duty sauce pan. Bring to a full rolling boil over medium heat, stirring constantly, for 4 to 5 minute. Remove from heat. Stir in marshmallows, morsels, nuts and vanilla extract. Stir vigorously for 1 minute or until marshmallows are melted. Pour into prepared baking pan; refrigerate for 2 hours or until firm. Lift from pan; remove foil. Cut into pieces.
For milk chocolate fudge use milk chocolate chips.