Grease a 9x13 baking dish. In a medium pan bring the sugar, butter and evaporated milk to a gentle boil over medium heat. Boil for 5 minutes. Stir constantly. Remove from heat, and add chocolate chips. Stir. Add marshmallow cream and vanilla. Using a handheld mixer, mix til smooth. Add in nuts (optional), and fold in. Pour into greased baking dish and let cool for 30-60 minutes before cutting into squares. We make this all the time with no nuts, and it still tastes amazing!