Ensure your unsalted butter is at room temperature for optimal creaminess.

In a mixer, blend softened butter with granulated sugar and light brown sugar until fluffy.

Mix in the egg yolk, salt, vanilla extract, and almond extract (optional).

Gradually add sifted all-purpose flour, mixing until just combined.

Divide the dough and roll into logs, then wrap tightly in parchment paper or plastic wrap. Chill in the refrigerator for at least 2 hours.

Preheat oven to 350°F (175°C).

Unwrap dough and slice into ¼-inch rounds, pressing colorful nonpareils onto edges if desired.

Arrange slices on a baking sheet lined with parchment paper, leaving space for spreading.

Bake for 10-12 minutes until golden edges appear.

Let cool on the sheet for a few minutes before transferring to a rack.