Grease a springform pan (26 cm Ø) well. For the shortcrust pastry base, knead flour, 100 g sugar, 1 vanilla sugar, 1 pinch of salt, 1 egg and 100 g cold butter in flakes first with the dough hook of the mixer and then with your hands to a smooth dough.
Roll out on the bottom of the springform pan and cut off the protruding edges of the dough. Prick several times with a fork and chill for about 30 minutes.
Dice the apricots and put them in a small pot. Pour apple juice over them and let them soak for about 10 minutes. Then bring to the boil while stirring, pour into a sieve, drain well and let cool off.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Cream 100 g soft butter, 150 g sugar and 1 vanilla sugar with the whisks of the mixer. Stir in 4 eggs individually.
Stir in the quark and pudding powder well. Fold in the apricots.
Fill the quark mixture into the springform pan and smooth it down. Bake in the hot oven on the lowest shelf for 60-70 minutes. After about 20 and 40 minutes baking time, remove the cake from the edge all around with a knife.
This way the surface does not crack. Take it out and let it cool down in the mould. Remove from the mould. Dust the edge of the cake with icing sugar.