In a large mixing bowl, cream together the butter, granulated sugar, and powdered sugar until fluffy and light in color, about 3-5 minutes. Add in the egg yolk, vanilla extract, and a pinch of salt, mixing well. Gradually incorporate the flour until a soft dough forms.

Wrap the dough tightly in plastic wrap and refrigerate for at least 1 hour.

Preheat your oven to 350°F (175°C).

Remove the dough from the refrigerator and roll it into 1-inch balls. Place them on prepared baking sheets, spaced 2 inches apart, and gently flatten each ball.

Bake in the preheated oven for 10-12 minutes until the edges are lightly golden.

Allow cookies to cool on the baking sheets for about 5 minutes before transferring to wire racks.

Arrange cooled cookies in decorative boxes or festive tins for gifting.