Notes: This is a great way to get your chocolate fix in warm weather since the chocolate is stirred into the toffee and so no melting on the fingers! It's great to snack on and nice at the end of a meal with coffee. I learned this from the head pastry chef at Valrhona Chocolates.
Place the sugar in a heavy-bottomed saucepan and caramelize on high heat stirring constantly. It will turn amber brown in about 5 minutes. When it is a uniform caramel color, add the butter, and stir it in. Once mostly combined, add the chocolate, and stir to blend. Pour it out onto a silpat or parchment lined sheet pan, and spread it with an offset spatula 1/8-inch thick. Let cool and break into small pieces. Store in an airtight container.