Chop the chocolate and melt in a bowl over a warm water bath. Remove the bowl from the water bath. Whip cream until stiff and chill
Separate eggs. Beat the egg yolks and 1 tbsp. sugar on a hot water bath until a thick, creamy mixture is formed. Remove bowl from water bath. Stir in chocolate, espresso and about 1/3 of the cream, then let it cool down to room temperature
Beat the egg whites until stiff, adding 1 tablespoon of sugar. First fold in the beaten egg whites, then the remaining cream. Pour the mousse into glasses and chill for at least 3 hours
Just before serving, heat the milk (do not bring to the boil). Froth the milk and distribute it on the glasses. Decorate with mocha beans and serve immediately
waiting time approx. 3 1/4 hours