Prepare the Dough: In a large bowl, beat the room-temperature unsalted butter and powdered sugar together until light and fluffy. Add the vanilla extract and egg yolk, mixing until well combined. Gradually add the all-purpose flour and salt, mixing on low speed until the dough starts to come together. Fold in the mini semi-sweet chocolate chips until evenly distributed throughout the dough.

Shape and Chill: Transfer the dough onto a piece of plastic wrap and shape it into a log approximately 10 inches (25 cm) in length. Wrap the dough tightly in the plastic wrap and refrigerate for about 2 hours, or until firm.

Slice and Bake: Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper. Remove the dough from the refrigerator and slice it into rounds about 1/4 inch (0.6 cm) thick. Place the cookies on the prepared baking sheet, spacing them about 1 inch (2.5 cm) apart. Bake for 12-14 minutes, or until the edges are just beginning to turn golden brown.

Cool and Serve: Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.