Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a medium bowl, combine the butter and both sugars using a silicone spatula, stirring for at least one minute until well blended. Add the egg yolk and vanilla, stirring until smooth.

Sprinkle the flour, baking soda, and salt over the butter mixture, then stir until just combined. Fold in the chocolate chips.

Scoop dough into mounds of about 2 tablespoons each, placing them a few inches apart on the baking sheet. You should have 5-6 dough balls. If desired, press a few extra chocolate chips onto the tops of the dough balls for added texture.

Arrange the dough balls to be higher rather than wider, which helps prevent them from spreading too much.

Bake for 9-12 minutes, until the edges start to turn golden brown and the centers are slightly under-baked.

Transfer the baking sheet to a wire rack to allow the cookies to cool and firm up before serving.