1/4 lb. unsweetened chocolate
2 tbsp. butter
3/4 c. half & half
2 c. sugar
3 1/2 tbsp. corn syrup
1/8 tsp. salt
1 tsp. vanilla extract

Butter an 8" or 9" square pan. Chop chocolate. Cut the 2 tablespoons butter into chunks. Combine half and half, sugar, corn syrup and salt in a heavy saucepan. Cook over low heat, stirring occasionally, until sugar dissolves (about 10 minutes). DO NOT BOIL. Stir in chopped chocolate. Let simmer, without stirring, over very low heat until a candy thermometer registers 234 degrees (about 30 minutes).