Mix quark, oil, milk, 1 packet of vanilla sugar, 50 g sugar and 1 pinch of salt. Knead 450 g flour and baking powder with the dough hooks of the hand mixer. Drain the apricots on a sieve.
Clean, wash and cut the rhubarb into pieces of about 3 cm. Grease a fat pan of the oven (approx. 32x39 cm). Roll out the dough in the pan. Spread the apricots with the curvature upwards and the rhubarb on top.
Sprinkle with 50 g sugar. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 50-60 minutes. In the meantime, whisk the softened butter and remaining sugar with the whisk of the hand mixer until foamy.
Stir in the remaining flour, vanilla sugar, almonds and 1 pinch of salt. After half the baking time, spread the crumble mixture on the cake. Let the finished cake cool down. Dust with icing sugar.