1 c. unsalted butter
3 oz. semi sweet chocolate
1 1/4 c. sweetened condensed milk
4 tbsp. corn syrup
2 1/4 c. brown sugar (firmly packed)

Grease baking pan. Mix butter, chocolate, sweetened condensed milk, corn syrup and brown sugar in large heavy sauce pan. Over medium heat, let mixture come to a boil. Let chocolate melt completely. Reduce heat to medium low and cook for 30 minutes, it will gently boil. Stir constantly with wooden spoon. It will be very thick. Pour into baking pan and cool on rack about 1 1/2 hours. Cut into 3/4 inch squares.