Mix the fat, 250 g sugar, 1 packet of vanilla sugar and 1 pinch of salt with the whisk of the hand mixer for 2-3 minutes until creamy. Stir in the eggs one after the other. Mix flour and baking powder, alternating with the milk. Spread the dough on a greased fat pan of the oven (32 x 38 cm). Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 15-20 minutes, remove from oven
Clean, wash and cut the rhubarb into small pieces. Bring juice and 25 g sugar to the boil in a pot, add rhubarb. Cover and simmer for 3-4 minutes. Stir starch with 1 tbsp. water until smooth. Stir into the boiling rhubarb, bring to the boil again and simmer for 1 minute. Put into a bowl and let cool for about 1 hour
In the meantime, soak gelatine in cold water. Mix quark, mascarpone, 50 g sugar and 1 packet of vanilla sugar. Squeeze the gelatine, dissolve in a pot, stir in 2-3 tbsp. mascarpone cream, stir into the remaining cream. Spread the mascarpone cream on the cake, leave to set in a cool place for about 1 hour. Cut the cake into approx. 72 pieces (approx. 4 x 4 cm), spread compote on the pieces
waiting time approx. 1 3/4 hours