Separate eggs. Beat the egg whites until stiff, add 75 g sugar, 1 packet of vanillin sugar and salt. Stir in the egg yolks one after the other. Mix flour, starch and baking powder. Sift over the egg cream and fold in. Line the bottom of a springform pan (24 cm Ø) with baking paper. Fill in sponge mixture and smooth it down.
Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 15-20 minutes. Let cool on a cake rack. Remove the base from the tin and place on a cake plate. Peel oranges and grapefruits so that the white skin is completely removed. Remove the fillets with a sharp knife between the parting skins. Squeeze the juice out of the parting skins. Put the fillets in a sieve and collect the juice. Spread about 1/3 of the fillets on the sponge cake. Stir cream cheese, sour cream, lemon juice, liqueur, 1 packet of vanilla sugar and 2-3 tbsp. sugar until smooth. Stir in sauce powder. Spread the cream on the sponge cake and chill for about 30 minutes. Spread the remaining fillets on the cream.
Put the fillets in a sieve and collect the juice. Spread about 1/3 of the fillets on the sponge cake. Stir cream cheese, sour cream, lemon juice, liqueur, 1 packet of vanilla sugar and 2-3 tbsp. sugar until smooth. Stir in sauce powder. Spread the cream on the sponge cake and chill for about 30 minutes. Spread the remaining fillets on the cream. Measure the juice and if necessary fill up to 250 ml. Mix the cake glaze powder, 3 tbsp. sugar and juice in a small pot with a wooden spoon. Bring the liquid to the boil while stirring. Spread over the fillets from the middle and chill for about 1 hour. Decorate with pistachios before serving
Measure the juice and if necessary fill up to 250 ml. Mix the cake glaze powder, 3 tbsp. sugar and juice in a small pot with a wooden spoon. Bring the liquid to the boil while stirring. Spread over the fillets from the middle and chill for about 1 hour. Decorate with pistachios before serving
waiting time approx. 2 1/2 hours