While the cupcakes bake, in a small saucepan add the sugar and shake the pan around until the sugar is in an even layer at the bottom of the pan. Place the pan over medium high heat and let the sugar start to melt without stirring, about 2-3 minutes. When sugar begins to melt, gently stir any granules that haven't melted into the the melted part. Sugar will go from a clear to golden color over the course of a few minutes, but goes from golden to dark very quickly. Take it just to the edge of burnt without going over -- should be a dark amber color.