Finely chop the chocolate. Bring the milk with gingerbread spices to the boil. Remove the pan from the heat, add the chocolate pieces and stir until the chocolate has melted. Mix the cream and cocoa and whip until thick. Beat the hot chocolate with the hand blender until frothy, pour immediately into preheated glasses. Spread the cocoa cream loosely on top with a spoon. Dust with a little cocoa powder before serving. If you like, you can refine the cocoa cream with brown rum or cognac.