Cream the softened European butter and granulated white sugar in a stand mixer on medium speed for 3 to 4 minutes until pale ivory and fluffy.
Add the egg yolks one at a time on low speed, then pour in the pure vanilla extract and sea salt. Mix until a smooth emulsion forms.
Sift in the all-purpose flour and mix on the lowest speed for 30 to 45 seconds, stopping the exact moment the flour disappears to avoid overworking.
Divide the dough, form into two 2-inch wide logs, wrap tightly in parchment paper, and chill in the refrigerator for at least 2 hours.
Preheat your oven to 175°C (350°F). Roll the chilled logs in coarse sanding sugar, then slice into uniform 1/4-inch discs.
Arrange on lined baking sheets with a 1.5-inch space and bake for 11 to 13 minutes until the rims are pale golden brown.