In a large pot, combine the sugar, butter and milk over medium heat. Stir until the sugar is dissolved and the mixture begins to boil. Boil for 5 minutes, stirring constantly.

Remove from the heat and stir in the chocolate chips. Continue stirring until melted and smooth.

Add the marshmallow cream, nuts (if using) and vanilla, stirring to combine.

Coat a 9x9 inch baking pan with cooking spray and line with a piece of parchment with a 2 inch overhang on two sides.

Spread the fudge mixture in the pan evenly and allow to cool until set, approximately 2 hours.

Remove the fudge from the pan by lifting with the parchment and set on a cutting board.

Cut into squares.