Mix fat, 50 g sugar and eggs. Mix flour, baking powder and salt and stir in. Spread the dough into a springform pan (24 cm Ø) greased at the bottom. Bake in a preheated oven (electric cooker: 175 °C/ gas: level 2) for about 20 minutes until golden brown.
Let it cool down. Soak 6 gelatine leaves. Peel oranges generously, so that the white skin is also removed. Remove the pulp between the parting skins. Squeeze the juice out of the parting skins and collect it.
Purée the orange juice, except for 5 tablespoons, and 2/3 of the fillets. Mix with curd cheese and the remaining sugar. Squeeze the gelatine, dissolve and stir into the quark cream. Chill until the mixture begins to gel.
Whip the cream until stiff and fold into the quark mixture. Spread the cream on the base. If necessary, immediately make grooves with a cake comb or fork and chill the cake. Soak the rest of the gelatine.
Mix the remaining juice and Campari. Squeeze the gelatine, dissolve and stir in. Dribble onto the cream. Decorate with orange filets and lemon balm.