Mix the butter with the sugar using a fork or whisk until foamy.

Then, one by one, add an egg, the vanillin, and the rum, mixing vigorously.

Add the almond flour to the dough and combine everything.

Place a disc of puff pastry on a baking sheet covered with parchment paper, and lightly wet the edges with water using a pastry brush (this is the best moment to insert the famous "figurine" or "fava" inside the cake).

Cover with a second disc of puff pastry, seal the edges and roll them slightly to prevent the filling from escaping.

Next, decorate: use a knife to draw diagonal lines on the surface of the pastry.

Spread the entire surface of the galette with the beaten egg yolk and bake.

Bake at 240°C for about ten minutes, then lower to 180°C for 20 more minutes.

Take out the galette and serve warm to your guests!