Bring the milk with the grated lemon zest to the boil. Crumble the chocolate and let it melt while stirring. Sprinkle the soft wheat semolina together with corn semolina, sugar and vanilla sugar and simmer everything for 5 minutes over low heat, stirring every now and then. Let cool slightly.
Separate the egg, stir in the yolks quickly, beat the egg whites into snow and fold in carefully.
I like the pudding both warm and cold in the fridge in summer. Consume within the next 24 hours, do not leave too long in the heat.