Separate eggs. Beat the egg whites and 3 tablespoons of lukewarm water until stiff. Finally, pour in 100 g sugar and vanilla sugar while stirring. Beat the egg yolks one after the other. Mix flour, cornstarch and baking powder, sieve onto the egg foam and fold in loosely.
Line the bottom of a springform pan (26 cm Ø) with baking paper. Fill in sponge cake mixture and smooth it down. Bake in the preheated oven (electric: 175 °C/ gas: level 2) for 25-30 minutes. Let the sponge cake cool down on a cake rack, remove from the tin and cut through once.
Place a cake ring around the lower cake base. Soak the gelatine in cold water. Warm the jam and spread it on the bottom cake base. Wash the lemon, dab dry and finely grate the peel.
Squeeze the lemon. Mix quark, 100 g sugar, lemon juice and zest. Squeeze out the gelatine, dissolve and mix with some quark mixture. Then stir into the remaining quark. Whip 200 g cream until stiff, fold into the quark mixture and place on the cake base.
Smooth the mixture and cover with the second base. Put the cake in a cool place for about 6 hours. Wash the strawberries, drain well and clean. Halve or slice the strawberries according to size.
Peel and slice the kiwis. Beat the rest of the cream and 1 teaspoon of sugar until stiff. Remove the cake from the cake ring and spread the cake edge with cream. Put the rest of the cream in a piping bag with a small star-shaped spout and decorate the edge of the cake with a delicate cord edge.
Gradually stir the cake glaze and remaining sugar with 1/4 litre of cold water until smooth. Bring to the boil while stirring and remove from the stove. Carefully fold the fruits into the glaze and place them in the middle of the cake (leave some glaze in the pot if necessary).
Chill the cake for another 20 minutes. Dust with icing sugar and serve decorated with melissa.