In a saucepan, combine 1/2 cup of the milk, the sugar, and chocolate. Cook and stir over medium heat until mixture comes to a boil. Stir in remaining milk and cream. Heat through, but don't boil.
Remove from heat. If you like, beat with a rotary beater until frothy. Serve hot in mugs. Top each with whipped cream and a dash of cinnamon. Serve with buttered toast for dunking, if you like. Makes 4 servings.