How to make
Divide the puff pastry into 12 rectangles. Distribute them some distance apart in an oven dish laid out with baking paper.
Sprinkle them with powdered sugar and bake at 390°F (200 °C) until golden, while taking them out after the first 5 min. of baking and sprinkling with powdered sugar again. Once they're done baking, take them out to cool on a cooking grid.
In the meantime, you can make the cream mixture. For it, beat the yolks with the sugar, starch and vanilla sugar until homogeneous. Pour in the milk a little at a time.
Boil the resulting cream on low heat until thickened, while stirring nonstop. Then pour it into a clean container and give it time to cool. Beat the full fat cream to snow. Add it to the cooled cream and stir. Pour this new mixture into a pastry bag.
Cut the cooled puff pastry sheets in 2 horizontally. Place 8 of them on a platter and make meringues from the cream on top of them using the pastry bag.
Arrange the cherries and place a 2nd layer of puff pastry sheets. Sprinkle cream again and add blueberry jam. Add the final puff pastry sheet and cover with meringues made from the cream.
Finally, sprinkle wild berries. If desired, you can sprinkle the pastries with powdered sugar and arrange some mint leaves too.