Mexican Hot Chocolate

Melt the chocolate in the top of a double boiler. In a separate heavy saucepan, heat the milk and cream on low until hot but not bubbling. When the milk mixture is hot add 3 tablespoons of it to the chocolate and mix well. Blend in the rest of the milk mixture, the sugar and the cinnamon. In a small bowl beat the eggs and vanilla. Add a tablespoon of the chocolate mixture in the eggs and beat well. Slowly stir the egg mixture into the chocolate. Whisk the hot chocolate briskly in the double boiler for 3 minutes, then serve immediately.