Butter 8" square pan.
In medium saucepan, combine butter, evaporated milk, sugar and salt.
Bring to a full boil over medium heat, stirring constantly.
Boil 4 to 5 minutes, stirring constantly; remove from heat.
Stir in marshmallows, morsels, vanilla and nuts.
Stir vigorously for 1 minute or until marshmallows melt completely.
Pour into prepared pan.
Refrigerate for 2 hours or until firm.
Cut into squares.
