Wash the lemon, grate dry and thinly grate the peel of 1/2 lemon. Halve the lemon, squeeze the juice. Cream fat, sugar, salt and lemon peel with the whisk of the hand mixer. Stir in the eggs one by one. Mix flour, starch and baking powder and stir in alternately with the milk. Finally add 1 tbsp. lemon juice
Grease a tray with 6 small Bundt cake troughs (each with a capacity of approx. 200 ml) and dust with flour. Pour the dough into the troughs and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 25-30 minutes. Then allow to cool slightly, turn out of the tin onto a cake rack and allow to cool
Stir icing sugar, 4 tablespoons of water and 4 teaspoons of lemon juice to a thick, smooth glaze. Cover cooled cakes with the icing and let them dry for about 1 hour. Mix mascarpone and vanillin sugar and stir in jam slightly (streaky). Fill the hollows of the cakes with mascarpone cream and serve immediately
waiting time approx. 2 hours