Melt the butter at a mild heat. Fill the biscuits into a freezer bag and close the bag. Finely crumble the biscuits with a dough roll. Mix crumbs and liquid butter
Place a cake ring or springform pan rim (26 cm Ø) on a cake plate lightly coated with oil. Fill in the biscuit mixture and press it down as a base. Chill for about 30 minutes.
Wash the lemon balm, pluck off the leaves and cut into fine strips. Mix quark, lime juice, vanillin sugar and pudding powder. Immediately stir in the lemon balm strips. Spread the quark cream on the biscuit base. Chill the cake for at least 2 hours
Whip the cream until stiff and fill into a piping bag with a large star-shaped spout. Spray the cream tuffs onto the cake. Decorate the cake with slices of lime, lemon balm and pistachios