Cut 8 circles from the cake base using a round cookie cutter (approx. 7 cm Ø). Drain the peaches and cut them into pieces except for one half. Mix quark, sugar, vanilla sugar, liqueur and lemon peel.
Whip the cream until stiff. Allow cream setting agent to trickle in. Add peach pieces and cream to the quark mixture and fold in. Spread the quark cream over 4 sponge cake circles and sprinkle with pistachios. Put the rest of the sponge cake circles on top.
Cut the remaining peach into slices and decorate the tartlets with it. Arrange on plates and serve decorated with lemon balm as desired. Chocolate sauce tastes good with it.