Cut butter into pieces. Separate 1 egg. Knead butter, flour, egg yolk and 75 g sugar to a smooth dough. Wrap the dough in foil and chill for about 30 minutes
Separate 1 egg. Mix quark, 100 g sugar and vanillin sugar with the whisks of the hand mixer. First fold in 2 eggs and 1 egg yolk one after the other, then stir in the pudding powder
Roll out the short pastry round (approx. 30 cm Ø) and line a greased tart mould with lift-off base (approx. 26 cm Ø) with it. Press down the edge and cut off any protruding edges. Prick the base several times and spread the fruit spread on top. Carefully pour the curd mixture over it and smooth it down. Bake the tart on the lower shelf in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for approx. 45 minutes.
Approx. 8 minutes before the end of the baking time, beat the remaining egg white until stiff, add 100 g sugar and add elderflower syrup. Beat the beaten egg whites until the sugar is dissolved. Fill the beaten egg whites in a piping bag with a perforated spout. Remove the tart at the end of the baking time. Spray the beaten egg whites onto the tart. Bake in the oven at the same temperature for 8-10 minutes
Waiting time approx. 25 minutes