Separate the eggs into yolks and whites. Mix the butter with the sugar until frothy. Then gradually add the egg yolks. Stir in the drained low-fat quark, mascarpone and custard powder.
Beat the egg whites to stiff snow and add the cornstarch to the curd mixture.
Line the juice pan of the oven with baking paper and spread the dough on it and decorate with the mandarins, then place in the preheated oven and bake at 180 ° for about 30-40 minutes.