In a large mixing bowl, beat together 1 cup of softened unsalted butter, 3/4 cup of granulated sugar, 1/4 teaspoon of salt, and 1 teaspoon of pure vanilla extract using a hand mixer or stand mixer. Mix on medium speed until the mixture becomes light and fluffy, about 2-3 minutes.

Add 1 large egg yolk to the creamed mixture and continue mixing until well incorporated, scraping down the sides of the bowl as needed.

Gradually add 2 cups of all-purpose flour to the butter mixture, mixing on low speed until just blended.

Turn the dough out onto a lightly floured surface and gently knead it a few times to bring it together. Shape the dough into a log, about 2 inches in diameter. Wrap the log tightly in plastic wrap and refrigerate for at least 2 hours.

Preheat your oven to 325°F (160°C) and line two baking sheets with parchment paper.

Using a sharp knife, slice the chilled dough into rounds approximately 1/8-inch thick. Place the slices on the prepared baking sheets, spacing them 1 inch apart.

Bake the cookies in the preheated oven for 16–18 minutes, or until the edges turn golden brown.

Once baked, remove the cookies from the oven and let them cool on the baking sheets for about 5 minutes. Then, transfer them to a wire rack to cool completely.