In a stand mixer fitted with a paddle attachment, beat the butter, sugar, and salt together until light and fluffy, 2 to 3 minutes.

Add the egg yolks and vanilla, and mix until combined. Stop and scrape down sides of the bowl during mixing.

Add in the flour mixture and mix on low speed just until incorporated. Dump the dough out onto the counter (the dough will be soft. Flour the surface and your hands as needed. Knead it a few times until the dough comes together into a single, solid ball. Shape it into a long shape, about 12 inches long.

Place it on a sheet of parchment paper or plastic, wrap it tightly and twist the ends to seal. Chill it in the refrigerator for at least an hour or up to 72 hours. (I've found the best way to keep the dough from flattening out on the bottom is to pop it into an empty cardboard paper towel roll.)

Once the dough is chilled, preheat the oven to 350°F. Line two large baking sheets with parchment paper.

Sprinkle sanding sugar on a clean surface or a rimming baking sheet. Unwrap the dough and roll the dough in the sugar until it is well coated. (Roll while pressing the dough down so the sugar sticks to the surface.)

Use a sharp knife to cut dough into slices about ¾-inch thick. Place the cookies on a parchment-lined baking sheet about an inch apart.

Bake for 10 to 12 minutes or until the edge is JUST turning golden brown. Let the cookies cool completely on the baking sheets.