Once the milk is warm, remove from heat and whisk in the chocolate, stirring until the chocolate is melted. For a thick hot chocolate, return to heat and cook at a very low boil for about 2-3 minutes, whisking constantly. Be careful and keep an eye on the mixture, as it may boil up a bit during the first moments.
Taste, and add brown sugar if desired.
Serve warm in demitasse cups, or small coffee or tea cups.
