Preheat the oven to 375F degrees and adjust the oven rack to the middle position. Line a baking sheet with a piece of parchment paper.
In a medium mixing bowl, add the room temperature butter and both sugars. Using a spoon, mix together until light and fluffy. You can also use a hand-held mixer, though it may be easier to just mix with a spoon.
Add in the egg yolk and vanilla extract - one at a time - and mix until combined. Move the mix to one side of the bowl with the spoon.
In the same bowl, add the flour, baking soda, and salt to the other side of the bowl. Stir the dry mix together first, then start to incorporate with the wet ingredients. Mix the cookie dough until thoroughly combined. Add in the chocolate chips and stir until just mixed in.
Transfer the bowl to the refrigerator to chill for at least 15 minutes.
Using a small cookie scoop or tablespoon, scoop 2 tablespoons of dough and form into ball and place on the prepared baking sheet. You will have enough dough to make 6 cookies. Place the cookies 2 inches apart on the baking sheet.
Bake for 8 to 11 minutes, or until the edges of the cookies are golden brown. Cool on the baking sheet for 10 minutes, then transfer to a wire rack to cool completely.