Crumble the chocolate and melt it with the butter over low heat. Separate the eggs, beat the egg yolks with the sugar until frothy and then carefully stir in the rum.
Whip the cream until frothy. Then beat the egg whites with clean utensils until frothy.
Now gradually stir the egg yolk cream into the dissolved chocolate. Conn. Carefully fold in the cream and egg whites and put everything in the fridge.