In a medium saucepan, combine sugar, evaporated milk, butter, and salt. Bring to a boil over medium heat, stirring constantly, and cook for 5 minutes.

Add chocolate chips and stir until fully melted and smooth.

Remove from heat and quickly stir in marshmallows, vanilla extract, and chopped nuts until well combined.

Pour mixture into a greased 8-inch square pan and spread evenly.

Let cool completely, then cut into squares and serve.