1) Combine first five ingredients, stirring over low heat until blended.Bring to a boil over moderate heat being careful not to mistake air bubbles for boiling. (VERY IMPORTANT)Boil slowly, stirring constantly for a full 5 minutes. (Also very important!).

2) Remove from heat and stir in vanilla and chocolate until chocolate is melted. Stir in nuts if needed.Turn into a 9 x 9 inch pan that has been sprayed with butter flavored cooking spray and cool completely.