How to Make It
In a microwave-safe cup, heat the milk at high power for 5 minutes, until boiling.
Add the chopped chocolate to a 1 1/2- to 2-quart heatproof pitcher. Pour the boiling milk over the chocolate and let stand for 1 minute. Mix the milk with the chocolate by rolling a whisk or wooden Mexican molinillo between the palms of your hands, until the hot chocolate is smooth and slightly frothy, about 3 minutes. Pour the hot chocolate into mugs, dust with cinnamon and serve.