In a large mixing bowl, cream the softened butter and sugar together until light and fluffy.
Add the egg yolk and mix until well incorporated. Gradually add the flour and salt, mixing just until a dough forms. Be careful not to overmix.
Shape the dough into a disc, wrap it in plastic, and refrigerate for at least 1 hour.
When ready to bake, preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.
Roll the dough out to about 1/4-inch thickness and cut into desired shapes using a cookie cutter. Arrange the cookies on the prepared baking sheet, spacing them about 1 inch apart.
Bake for 10-12 minutes, or until the edges are lightly golden. Allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
Enjoy the delectable French butter cookies with a cup of tea or coffee.
Consider experimenting with flavor variations by infusing the dough with the essence of vanilla, citrus, or fragrant herbs.Chill the dough thoroughly, handle it gently, and watch the oven vigilantly for best results.