Bring the milk to a boil in a saucepan and remove from the stove. Break the chocolate into pieces and add to the hot milk. Stir until it has melted. If you still have pieces in it, simply reheat everything.
Then stir in the coffee liqueur and pour into 4 heat-resistant glasses. Stir the cream until creamy, but do not pour it firmly and evenly onto the chocolate milk. Sprinkle each with a little cinnamon powder and serve immediately.