Gather all ingredients.
Grease a 9x13-inch pan.
Mix sugar, butter, and evaporated milk in a large, heavy saucepan over medium heat, stirring to dissolve sugar. Bring mixture to a full boil and cook for 5 minutes, stirring constantly.
Remove from the heat and add chocolate chips; stir until chocolate chips are melted and mixture is thoroughly combined.
Stir in marshmallow creme until incorporated. Mix in walnuts and vanilla.
Transfer fudge to the prepared pan and use an offset spatula to spread out and flatten.
Let cool for at least 1 hour before cutting into squares. Enjoy!
