Mix flour and baking powder, put it in a bowl with 400 g sugar. Whisk eggs, oil and juice. Pour into the bowl and whisk everything together with the whisk of the hand mixer to a smooth, liquid dough. Grease the fat pan of the oven well. Add the dough and smooth it down. Bake in the preheated oven (electric cooker 200 °C/ convection oven: 175 °C/ gas: level 3) for 15-20 minutes.
Let them cool down. Drain mandarins well, put some aside for decoration. Mix vanillin sugar and cream thickener. Whip cream until stiff. Allow the cream mixture to trickle in. Stir the sour cream until smooth, stir in the cream. Fold the mandarins into the cream. If necessary, place a baking frame around the base. Pour the cream on the cake base, smooth it down. At least 6 hours, it is better to put it in a cool place overnight. Cut the cake into rectangles.
Stir the sour cream until smooth, stir in the cream. Fold the mandarins into the cream. If necessary, place a baking frame around the base. Pour the cream on the cake base, smooth it down. At least 6 hours, it is better to put it in a cool place overnight. Cut the cake into rectangles. Mix 60 g sugar with cinnamon, sprinkle cake pieces with it. Decorate with set aside mandarins and lemon balm leaves
waiting time approx. 7 hours