Divide the puff pastry into two portions.
Roll out one piece of puff pastry to a thickness of 3 mm (0.1 in) on a lightly floured surface or between two sheets of parchment paper, then place it in the refrigerator for 10 minutes to prevent it from shrinking during cutting.
Then, remove the pastry from the refrigerator, and using a sharp knife or cutter, cut out a disc, using a pastry ring of 24 or 26 cm (9.5 or 10.2 in) as a guide.
Repeat the process with the second half of the puff pastry.
Fill the first disc with almond cream, leaving a 2 to 3 cm (0.8 to 1.2 in) border around the edge.
Add a fève or a nut, it's optional but in tradition it is considered mandatory. Whoever finds it will be crowned king or queen for the day. The fève is usually ceramic, so be sure to inform your guests that there is one inside. You can also replace it with a nut. Place it in the cream along the edge. Moisten the empty edges with a bit of water to help the second disc adhere. You can also brush the edges with egg yolk, ensuring it does not spill over the sides, as this would hinder the puff pastry from rising properly.
Cover with the second disc, gently smooth the top with your hand to remove any air, and press the edges with your fingers to seal the two discs together.
Flip the galette onto a baking tray lined with parchment paper.
Note : You can store the galette, tightly wrapped, in the refrigerator until the next day, either before or after flipping it.
Press firmly along the edges to seal the border (the 2 to 3 cm / 0.8 / 1.2 in without cream).
Using the blunt side of a knife, scallop the edges as shown in the photo. This step is optional.
Brush the top of the galette with beaten egg (1 yolk and a bit of white) using a pastry brush, then let it rest in the refrigerator for at least 1 hour or longer. Only brush the top, avoiding the sides, to ensure the puff pastry rises properly.
Once the first layer of egg wash has set, apply a second layer and then decorate the galette by gently tracing patterns of your choice on the surface using a knife or a toothpick, wiping after each pass.
Using the blunt side of a knife, trace arcs starting from the center of the galette. You can use a cake board or a plate to help create the arcs neatly.
Begin with light strokes, and once you’ve finished, go over them a second time (this time without the plate) to make the arcs more distinct. Be careful not to press too hard with the knife; work gently to avoid piercing the pastry.
After the second pass with the knife to properly trace (the arcs), make sure to go gently to avoid piercing the dough.