Chop the chocolate and melt it over a warm water bath. Leave to cool at a lukewarm temperature. In the meantime, separate the eggs. Beat the egg yolks, sugar and vanilla sugar in a tall beaker with the whisks of the hand mixer until creamy. Separately beat cream and egg whites until stiff. Stir the whipped egg yolk into the chocolate. Stir in the liqueur.
Fold in half of the cream immediately with a whisk. Fold in the rest of the cream. Fold in the beaten egg whites in portions and chill for at least 3 hours. Peel oranges and grapefruit so that the white skin is completely removed. Remove the fillets with a sharp knife between the parting skins. Chop the pistachios and almonds. Layer cream with citrus fillets, almonds and pistachios in 4 dessert glasses
3 hours waiting time