Place the puff pastry slices next to each other and defrost at room temperature for about 10 minutes. Mix sugar, vanillin sugar, salt and flour. Bring milk and fat to the boil in a saucepan.
Add the sugar mixture to the milk while stirring vigorously. Bring to the boil briefly and remove from the stove. Pour into a bowl, cover and set aside, let cool slightly. Cut out 2 circles (9 cm Ø) from each of the dough slices, roll out slightly larger if necessary.
Grease the troughs of a muffin tin (12 troughs). Line with the dough circles, press well. Put them in a cold place. Wash the apricots, cut them crosswise and blanch with hot water. Quench cold and peel the skin.
Halve and stone the apricots. Stir egg and egg yolks into the cream. Spread the cream in the hollows, add 1 apricot half each. Bake in the preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for 15-20 minutes.
Allow to cool briefly, remove the tartlets from the troughs and let them cool on a cake rack. Sprinkle with chopped pistachios and serve decorated with mint.