Grease twelve troughs of a muffin tray and dust with flour. Drain the apricots, dab dry well with kitchen paper.
For the dough, mix 1 egg, oil, buttermilk, sugar, vanilla sugar, 1 pinch of salt, lemon zest and juice with the whisks of the mixer. Stir in flour and baking powder briefly. Spread the dough evenly into the bowls.
For the filling, mix mascarpone, quark, 1 egg, starch and jam. Fill 1 apricot half each with the mascarpone mixture, place the 2nd half directly on top and press carefully into the dough.
Spread the rest of the mascarpone cream on the apricots. Bake in a hot oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer) for 25-30 minutes. Let cool for about 15 minutes. Lift out of the trays and allow to cool. Dust with icing sugar.