Separate the eggs, beat the egg whites with 3 tablespoons of water until stiff, pour in 100 g sugar and 1 sachet of vanillin sugar. Fold in the egg yolks bit by bit. Mix flour, starch and baking powder, sieve onto the egg foam and fold in. Line the bottom of a springform pan (26 cm Ø) with baking paper. Fill in sponge cake mixture, smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 20-25 minutes.
Let them cool down. Remove baking paper. Cut the sponge cake in half horizontally and place a springform pan rim or cake ring around the bottom. Divide the upper cake base into 12 segments. Drain mandarin oranges on a sieve. Soak the gelatine in cold water. Stir the quark, lemon juice and zest, 125 g sugar and 1 packet of vanilla sugar until smooth. Whip the cream until stiff. Squeeze the gelatine, dissolve and mix with 2 tablespoons of quark mixture. Stir into the remaining quark, fold in cream and mandarins. Spread the cream on the lower cake base and smooth it down. Add the divided second cake layer.
Stir the quark, lemon juice and zest, 125 g sugar and 1 packet of vanilla sugar until smooth. Whip the cream until stiff. Squeeze the gelatine, dissolve and mix with 2 tablespoons of quark mixture. Stir into the remaining quark, fold in cream and mandarins. Spread the cream on the lower cake base and smooth it down. Add the divided second cake layer. Chill for at least 6 hours, preferably overnight. Remove the cake from the edge of the mould with a knife, dust with icing sugar
6 1/2 hours waiting time