Roll out your puff pastry to a height of about 2 mm, and form 16 squares of about 10 cm. Set aside in the refrigerator until you are ready to prepare the cake.
Work the butter with a fork. Add the egg and mix well.
Mix in the flour and sugar. Then add the almond powder and mix until you have a smooth paste.
Place 8 pieces of dough on a parchment paper-lined baking sheet. Spread the filling evenly over the surface of each pastry square, leaving a border of about 1 cm.
Place the bean in the filling of one of the cakes.
Moisten the edges of the dough with a very small amount of water, then place the remaining dough squares on top. Seal the dough by pressing your fingers on the edge.
Put the patties in the refrigerator for 30 minutes.
Preheat oven to 200°C (400°F).
Take out the mini patties. Brown them with the egg yolk mixed with the milk. Make a small hole in the center of each cake. Using a sharp knife, make the decoration of your choice on the top of the cake (you have to make cuts but be careful to avoid cutting the dough).
Bake for about 30 minutes, until the mini patties are golden brown.