Divide the puff pastry into two portions.
Roll out the puff pastry to a thickness of 3 mm (about 1/8 inch), then refrigerate for 10 minutes to prevent it from shrinking when cut.
Remove the pastry from the refrigerator and, using a 24 or 26 cm (about 9 1/2 or 10 1/4 inches) pastry ring, cut out a disc.
Repeat with the second portion of puff pastry.
Spread the almond cream over the first disc, leaving a 2 to 3 cm (about 3/4 to 1 1/4 inches) border all around.
Note: As is traditional, remember to tuck a small ceramic fève into the almond cream, about 2 cm (3/4 inch) from the edge. You can replace it with a whole almond. Whoever finds it will be crowned king or queen for the day.
Lightly moisten the uncovered edges with a little water to help the second pastry layer adhere.
You can also brush the edges with egg yolk, making sure it does not spill over the sides, as this would prevent the puff pastry from rising properly.
Cover with the second rolled out pastry. Gently smooth the top with your hand to release any trapped air, then press the edges with your fingers to seal the two layers together.
Flip the galette onto a baking sheet lined with parchment paper.
Note: You can keep the galette tightly wrapped in plastic wrap in the refrigerator until the next day, either before or after flipping it.
Press firmly around the edge to seal the borders well, focusing on the 2 cm (about 3/4 inch) area without filling.
Using the back of a knife, flute the edges as shown in the photo. This step is optional.
Brush the top of the galette with beaten egg (1 egg yolk mixed with a little egg white) using a pastry brush, then let it rest in the refrigerator for at least 1 hour, or longer. Brush only the top, without touching the sides, so the puff pastry can rise properly.
Once the first egg wash has set and no longer sticks to your finger, apply a second coat, then score the galette with the pattern of your choice.
Using a plate as a guide, trace arcs from the center to the edge of the galette with the back of a knife. Wipe the knife after each pass.
Start with light strokes, then go over them a second time (without the plate this time) to make the arcs more pronounced. Be careful not to press too hard, so you don’t pierce the pastry. (Edit 2023: I no longer do the second pass. One pass after the second egg wash is enough.)