In the bowl of a stand up mixer, beat the butter with the icing sugar until creamy. Add the almond flour and the salt and mix well. Then add one egg and the white of the other one (reserve the yolk for later). Mix well until incorporated. Add the vanilla extract and mix until blended with the rest of the ingredients. Cover and refrigerate the mixture for at least 1 hour.
In a small bowl, mix the remaining yolk with 1 Tbs cold water. Beat to mix, cover and refrigerate.
Thaw puff pastry according to instructions on box. On a lightly floured surface, extend one of the puff pastry sheets. Cut out the corners to form a circle and place on a cookie sheet lined with parchment paper. Follow the same process with the second puff pastry sheet.
Spread the filling over the dough on the cookie sheet, leaving a 1-inch border uncovered. Lightly press the charm on the filling. Moisten the border of the dough with cold water, place the second circle of puff pastry on top and press the edges to seal. With a butter knife, scallop the edges by lightly pressing into the dough. Refrigerate for 30 minutes.
Heat the oven to 425ºF.
Brush a thin layer of the yolk glaze over the galette, avoiding the border so the glaze doesn’t drip down the rim (otherwise the galette won’t rise). With the tip of a paring knife, etch a design on the top of the galette (I started in the center and drew a fan). Cut 5 or 6 small slits on the galette as steam vents.
Turn the heat down to 400ºF and bake the galette for 20 minutes, checking after 15 minutes. The galette should puff up and be deeply golden (bake a few minutes longer if necessary).
Remove from the oven and let cool for at least 20 minutes (the galette will deflate slightly).