Combine butter and sugars in a large bowl (or in the bowl of a stand mixer) and use an electric mixer to beat until creamy.

Add egg yolk and stir well.

Add salt, vanilla extract, and almond extract (if using). Beat until well-combined.

With mixer on low speed, gradually add flour until completely combined. Dough may be crumbly.

Add nonpareils (if using) and fold into dough.

Divide dough into 2 parts and transfer each part onto a sheet of wax paper. Work dough into a 2" wide log shape.

Transfer to the refrigerator to chill for at least 2-3 hours.

Once dough has chilled, preheat oven to 350ºF (175ºC) and line a cookie sheet with parchment paper.

Remove one cookie dough log from the refrigerator and use a sharp knife to cut into ¼" slices.

Place slices on prepared cookie sheet about 1" apart and bake for 10-12 minutes or until edges are just beginning to turn golden brown.

Allow to cool on baking sheet before serving. If desired, dip cooled cookies in chocolate and top with additional sprinkles.