Generously butter an 8 or 9 inch baking dish and set aside.
Microwave morsels and milk in 1 1/2 quart microwavable bowl on high for 2 minutes, stirring after 1 minute. Stir until the morsels are completely melted and smooth.
Stir in salt, vanilla, nuts and marshmallows and quickly spread into prepared dish.
Refrigerate until firm, about 2 hours. Makes about 3 pounds. Enjoy!