Serves: 64 (1-inch) pieces
Grease an 8 by 8-inch pan with butter. In a heavy-bottomed saucepan, combine the sugar, chocolate, 1 1/2 tablespoons of the butter, half-and-half, and corn syrup.
Over medium heat, stir with a wooden spoon until sugar is dissolved and chocolate is melted. Increase heat and bring to a boil. Reduce heat to medium-low, cover, and boil for 3 minutes.
Remove the cover and attach a candy thermometer to the pot. Cook until the thermometer reads 112°C. Remove from the heat and add the remaining butter. Do not stir.
Let the mixture cool for 10 minutes or until it drops to 54°C. Add vanilla and nuts, if desired, and mix until well-blended and the shiny texture becomes matte. Pour into the prepared pan.
Let sit in cool dry area until firm. Cut into 1-inch pieces and store in an airtight container for up to a week.