Gather all your ingredients and allow the unsalted butter to reach room temperature for about 30 minutes. Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, add the room temperature butter and granulated sugar. Cream the mixture on medium speed for about 3-4 minutes until light and fluffy.

Add the powdered sugar and continue mixing for another minute until well incorporated.

Reduce mixer speed and pour in the vanilla extract and egg yolk. Beat together for 1-2 minutes until creamy and smooth.

In a separate bowl, whisk together the all-purpose flour and salt. Gradually add this flour mixture into the wet ingredients, mixing on low speed until just combined.

Cover the bowl tightly with plastic wrap and refrigerate the dough for about 30 minutes.

Once chilled, form small balls of dough about 1 inch in diameter and place them on the prepared baking sheet, leaving space between them.

Bake for 10-12 minutes until the edges are golden and the centers appear set. Allow to cool before transferring to a wire rack.

Store in an airtight container at room temperature for up to a week.