Preparation :

• Place butter in a large bowl and sift in the flour, mixing well.
• Separate the egg yolks.
• Add powdered sugar, egg yolks, lemon zest, vanilla, and baking soda to the flour-butter mixture and knead into a dough.
• Let the dough rest at room temperature for 20 minutes.
• Tear small walnut-sized pieces, roll them, and make an indentation in the center. Dip first in egg white, then in sugar, and place on a baking tray.
• Fill the indentations with jam.
• Bake in a preheated oven at 180°C for 20 minutes.