Prepare all the ingredients.
the puff pastry to 3 mm thickness.
Mix the egg yolk and water and brush the dough to make it golden.
Do a first round of cutting with a round crimped cookie cutter
Go on...
...to obtain puff pastry crescents.
Draw the fleurons on the whole pastry...
...and put them on a slightly greased baking sheet.
Put in a warm oven at 180/200°C (356/392°F).
Bake for 15 to 20 minutes. They should rise.
Do not open the oven until the fleurons are totally baked and reached their golden color.
When finished, take out of the oven and leave to cool. Remove from the baking sheet with a metal spatula.