Separate eggs. Beat the egg yolks, vanilla sugar and 20 g sugar with the whisks of the hand mixer in a high mixing bowl for about 5 minutes until very creamy. Slowly add the egg liqueur. Beat egg whites and cream separately until stiff. Fold one after the other into the egg yolk mixture. Pour the parfait mixture into small moulds (6x6 cm, 150 ml) and freeze overnight. Caramelise 50 g sugar in a pan until light brown.
Stir in almond slivers. Pour spoonfuls of white sugar onto baking paper immediately. Let it cool down. Just before serving, dip parfait cups in hot water, loosen the rim with a small knife and turn parfaits out onto plates. Let thaw for 5 minutes. Pour eggnog around the parfait as desired. Decorate with almond brittle and strawberries