Prep your equipment: Line two baking sheets with parchment paper. Set oven racks in the upper and lower thirds. Have plastic wrap ready for chilling the dough.

Cream the butter and sugar: In a large bowl, beat the softened butter and granulated sugar together until light and creamy, about 2–3 minutes. Scrape the bowl once to ensure even mixing.

Add yolks and vanilla: Beat in the egg yolks and vanilla until smooth and glossy. The mixture should look slightly thick and cohesive.

Combine dry ingredients: In a separate bowl, whisk the flour and salt. Add this mixture to the butter mixture in two additions, mixing on low just until the dough comes together. Don’t overmix.

Shape and chill: Divide the dough in half. Roll each half into a log about 1.5 inches (4 cm) in diameter. If using turbinado sugar, roll the logs in the sugar to coat the sides. Wrap tightly in plastic and chill for at least 2 hours (or up to 3 days). Cold dough is key for clean slices.

Preheat the oven: When you’re ready to bake, preheat the oven to 350°F (175°C).

Slice the cookies: Using a sharp knife, slice the logs into 1/4-inch (6–7 mm) rounds. If any slices crack at the edges, gently press them back into shape.

Arrange and bake: Place the slices on the prepared sheets, spacing them about 2 inches apart. Bake for 12–15 minutes, rotating the pans halfway through, until the edges turn light golden and the centers are set.

Cool completely: Let the cookies rest on the baking sheet for 3 minutes, then move them to a wire rack to cool fully. They will crisp up as they cool.

Optional finish: Once cool, dip half the cookie in melted dark chocolate and let set on parchment. A sprinkle of flaky salt adds a lovely contrast.