Line a 9x13-inch baking pan with aluminum foil and butter the foil lightly. Set aside.

In a large heavy saucepan, combine sugar, butter, and evaporated milk. Bring to a full rolling boil over medium heat, stirring constantly.

Continue boiling for exactly 5 minutes, stirring constantly to prevent scorching. Remove from heat.

Quickly stir in chocolate chips until completely melted and smooth.

Beat in marshmallow creme, vanilla, and nuts if using with a wooden spoon until smooth.

Pour immediately into prepared pan and spread evenly. Let cool completely at room temperature.

Once set, lift fudge out using the foil, cut into 1-inch squares, and store in an airtight container.