Separating eggs. Beat the egg whites and 3 tablespoons of cold water until stiff, adding 125 g sugar and 1 packet of vanillin sugar. Fold the egg yolks into the beaten egg white. Mix flour, starch and baking powder, sieve over the egg mixture and fold in. Grease a square springform pan (24 x 24 cm), pour in the mixture and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 30 minutes. Remove the sponge cake from the oven, remove from the rim after approx. 10 minutes and let it cool down.
Soak gelatine in cold water. Wash the lime and grate dry. Grate the skin thinly and squeeze the lime. Mix quark, 100 g sugar, 1 packet of vanillin sugar and lime juice. Crush/pulp 80 g pistachios, lime zest and approx. 3 tablespoons of the quark mixture in the universal chopper. Squeeze and dissolve the gelatine. Stir in 3 tablespoons of quark cream, then stir back into the remaining cream. Halve the cream. Mix one half with the pistachios. Whip the cream until stiff and cut in half. Stir 1 half each into the quark and pistachio cream.
Stir in 3 tablespoons of quark cream, then stir back into the remaining cream. Halve the cream. Mix one half with the pistachios. Whip the cream until stiff and cut in half. Stir 1 half each into the quark and pistachio cream. Put the edge of the springform pan around the sponge cake again. Fill the quark and pistachio cream with a tablespoon into the form, smooth it down and put it in a cool place for at least 1 hour. Cut out small and large balls from the melon slices with a ball cutter. Finely chop 20 g pistachios. Cut the cake into 12 pieces. Sprinkle with pistachios and decorate with melon balls
Put the edge of the springform pan around the sponge cake again. Fill the quark and pistachio cream with a tablespoon into the form, smooth it down and put it in a cool place for at least 1 hour. Cut out small and large balls from the melon slices with a ball cutter. Finely chop 20 g pistachios. Cut the cake into 12 pieces. Sprinkle with pistachios and decorate with melon balls