Sort blackberries. Wash lemon thoroughly, rub dry, finely grate peel and squeeze juice. Beat the eggs, sugar, vanilla sugar and salt with the whisk of a hand mixer until creamy white. Add the quark, lemon zest and 3 tablespoons of lemon juice and stir in. Stir in the pudding powder well. Pour half of the quark mixture into a well greased springform pan (24 cm Ø), spread half of the blackberries evenly on top, add the remaining quark mixture and smooth down.
Bake in a preheated oven (electric cooker: 175 °C/ convection oven: not suitable/ gas: level 2) for 60-65 minutes. Cover with aluminium foil after about 40 minutes. Take the cake out of the oven and let it cool down on a grid. Then remove from the mould. Dust with icing sugar and cover with remaining blackberries. Serve decorated with mint