Grease a 9 X 13 " pan.  Alternative and much easier is to line a 9 X 13" pan with parchment paper, this allows a much quicker release and clean up.In a medium pot, mix sugar, butter and milk.Bring the mixture to a full boil using medium heat, stirring constantly so the sugar dissolves and the mixture does not burn on the bottom of the pot.Boil for five minutes. This is important! Five minutes exactly !!Remove the thickened mixture from the heat and add chocolate chips.Add the marshmallow crème and vanilla.Add nuts if desired.Pour into the prepared pan to cool.