Melt the coarsely chopped couverture in a hot water bath, set aside. Beat egg and egg yolk in a metal bowl in a hot water bath until foamy.
Stir in couverture and brandy or rum.
Allow to cool to lukewarm. In the meantime, whip the cream until semi-stiff and fold in. Pour the mousse into a bowl, cover and chill for 2 hours before serving.
