Step 1

Preheat the oven to 375°F (190°C). Line a baking sheet with parchment paper or a silicone mat. Beat the butter and sugar together on medium speed until light and fluffy - about 1 minute.

Step 2

Add 2 egg yolks and the vanilla extract, and mix on medium speed until they're incorporated. Stop to scrape the bowl with a rubber spatula before resuming the mixing. Add the flour in and mix on low speed just until the dough starts to clump together.

Step 3

Lightly flour a wooden board or counter before placing the mass of dough onto it. Use your hands to shape the dough into a big ball. Then sprinkle some flour on top of the dough before using a rolling pin to roll the dough out. As soon as the dough starts sticking to your pin, sprinkle a pinch of flour on the dough, then resume rolling. Roll your dough out until it's approximately 1/4" thick.

Step 4

Use medium round cookie cutters (2.25"/5.75 cm) to cut out round cookies from the dough. Use a sharp-edged spatula to transfer the cookie rounds onto the baking sheet. Place 12 cookies on the baking sheet, spaced out from each other. Beat the remaining yolk in a small bowl. Use a fork to make a cross-hatch pattern on the cookies (drag the fork down vertically on the cookie, then drag the fork across horizontally). Brush the tops of the cookies with the beaten egg yolk.

Step 5

Bake the cookies for 12 to 15 minutes, until they're a deep golden color. Transfer the cookies to a wire cooling rack to cool completely.