Finely mash the butter biscuits and orange cookies. Mix with 100 g sugar and orange zest. Melt butter and knead with cookie crumbs. Grease a fat pan (32 x 39 cm), spread the biscuit mixture evenly on it and press it down. Whip cream until stiff. Whip the eggs for about 5 minutes. Add 200 g sugar.
Add quark, sour cream, flour and semolina, stir in. Fold in cream. Pour the quark mixture onto the base and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for about 1 hour. In the meantime, peel the citrus fruits so that the white skin is completely removed. Remove the fillets from the parting skins with a sharp knife and spread them on the cake. Decorate with orange pastry