In a large mixing bowl, beat softened butter, granulated sugar, salt, and pure vanilla extract until smooth and creamy. Add the egg yolk, mixing until well combined.

Gradually mix in the all-purpose flour, stirring gently until just incorporated.

Turn the dough onto a floured surface and knead gently. Shape into a log, wrap in plastic wrap, and refrigerate for at least 2 hours.

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

Slice the chilled dough into 1/8-inch thick rounds and place them 1 inch apart on the baking sheet. Bake for 16–18 minutes until golden brown.

Allow cookies to cool on a wire rack before serving.

Optional: Dust cooled cookies with powdered sugar.