Kurabye

Make the base: Place softened butter and powdered sugar in a mixer bowl. Beat until smooth and fluffy.

Carefully separate the egg white from the yolk, making sure no yolk gets into the white. Add the white to the butter mixture and beat thoroughly until fully combined.

Start kneading the dough. Sift the flour through a sieve to aerate it. Gradually add the flour to the mixture while continuing to beat. Finally, add the vanilla sugar and knead into a soft, pliable dough.

Shape the cookies: Transfer the dough into a piping bag (if you don't have one, a sturdy plastic bag with the corner cut off will work).

Line a baking sheet with parchment paper. Pipe small portions of the dough, leaving at least 1 cm of space between them. Make an indentation in the center of each piece and add a little jam or fruit preserves.