Cream fat, 200 g sugar and Citro-back. Gradually stir in eggs, alternating with 50 g flour. Mix 200 g flour and baking powder and stir in briefly together with 100 g cream. Pour the dough into a greased, flour-dusted fat pan of the oven and smooth it down. Bake in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: level 3) for approx. 15 minutes. Let the lemon base cool down. Mix quark, 150 g sugar and vanillin sugar.
Whip 250 g cream and cream firmer until stiff and fold into the quark. Spread the quark cream on the lemon base. Cut the cake crosswise into approx. 7 cm wide strips and lift them from the fat pan. Spread the strips with groats and cut into 4-5 pieces each. Whip 150 g cream until semi-stiff and put a small blob of cream on some pieces. Decorate with lemon and arrange the pieces on a large plate. Serve immediately