Do not boil simple syrup for more than the time it takes to dissolve. It you overcook your syrup it will eventually become caramel.Any English toffee bar or bits will work well for this recipe.This simple syrup will be thicker than plain simple syrup, this is because of the addition of brown sugar and the toffee bits. It still works great in drink recipes. I’m calling this out so you don’t think you made it wrong.