Step 1: Prepare the Dough

1. In a large mixing bowl, beat butter and sugar until creamy and smooth.
2. Add egg yolk and vanilla extract, mixing until fully combined.
3. Gradually add flour and salt, mixing until a soft dough forms.

Step 2: Chill the Dough

1. Shape the dough into a log (for round cookies) or flatten into a disc (for cut-out cookies).
2. Wrap in plastic wrap and chill for at least 1 hour.

Step 3: Shape & Bake the Cookies

1. Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.
2. If using a log shape, slice into ¼-inch rounds. If rolling out, use a cookie cutter.
3. Sprinkle with coarse sugar for extra crunch (optional).
4. Bake for 12-15 minutes, until edges are lightly golden.

Step 4: Cool & Serve

1. Let cookies cool on the baking sheet for 5 minutes, then transfer to a wire rack.
2. Enjoy with tea, coffee, or as a light dessert!