Melt the butter in a small pot. Chop 3 biscuits into large pieces, put aside. Finely chop the remaining biscuits in the universal chopper. Mix the crumbs with the butter. Lightly coat the bottom of a springform pan (20 cm Ø) with oil. Press approx. 2/3 of the crumb mixture onto it to form a smooth base
Mix the quark, sour cream and lemon peel. Mix pudding powder, vanilla sugar and sugar, stir into the quark. Spread half of the quark mixture on the crumb base and smooth it down. Spread the rest of the crumbly dough on top. Add the remaining quark mixture and smooth it down. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 1 hour, take out and let cool down on a cake rack for approx. 2 hours
Coarsely chop dark chocolate and melt it over a warm water bath. Add 70 g cream and stir until smooth, let it cool down a bit. Do the same with the white chocolate and 30 g cream. Cover the cheesecake with the dark icing. Coarsely spread the white icing on top and marble with a toothpick. Decorate the edge with pieces of biscuit and chill the cake for about 30 minutes
waiting time approx. 1 3/4 hours