Professional results, no candy thermometer required! I tested this toffee over and over for a cooking demonstration recently, which is how I discovered it can be made in 17 minutes. Great for gift giving, if you can resist eating it all! I make the batch with half semisweet chocolate, half white chocolate. Milk chocolate never seems to firm up enough. I once overcooked this to a deep nut brown, and suddenly it separated into a sugary mass and a sort of clarified butter. Still worked, though, and tasted great.