Defrost the puff pastry slices side by side. Place slices on top of each other, roll out to a thickness of approx. 2 mm and cut out 12-14 circles (7 cm Ø). Place the dough remains on top of each other (do not knead), roll out again and cut out 4-6 circles. You need 16 circles. Mix egg yolk and 2 tablespoons of cream.
Prick circles several times with a fork and brush with the egg. Put circles on a baking tray lined with baking paper. Bake in a preheated oven (200 °C/ convection oven: 175 °C/ gas: level 3) for about 15 minutes until golden brown. Take the puff pastry out of the oven and let it cool down. Wash and halve the plums, remove stones. Cut fruits into 8-12 slices. Wash lemon balm, dab dry and remove leaves. Spread 1 teaspoon of plum jam on the pricked side in 8 circles. Whip the rest of the cream until stiff, allowing the vanillin sugar to trickle in. Put the cream into a piping bag with a star-shaped spout and squirt some cream onto the jam.
Wash lemon balm, dab dry and remove leaves. Spread 1 teaspoon of plum jam on the pricked side in 8 circles. Whip the rest of the cream until stiff, allowing the vanillin sugar to trickle in. Put the cream into a piping bag with a star-shaped spout and squirt some cream onto the jam. On the other 8 circles, spread the jam on the underside and place it on the cream. Place a cream tuff on all tartlets and decorate with plum wedges and lemon balm. Dust with icing sugar