Mix the flour, baking soda, and salt in a small bowl and set it aside.
Cream together the butter, brown sugar, and granulated sugar in a medium-sized bowl. I like to do this with a hand mixer, but you can also mix this by hand if you prefer. Mix until it is light and creamy, about 1-2 minutes.
Add the egg yolk and vanilla. This time, only mix until it is combined. To this, add in the flour mixture and again, mix only until it is combined.
Last is the chocolate chips. I like to mix these in by hand. The dough will need to be chilled for at least an hour before baking. You can either cover the bowl with saran wrap and place it in the fridge. Or you can scoop out the cookies onto your parchment-lined baking sheet- my preferred method.
Let the cookies chill for at least one hour. At the end of the chill time, preheat the oven to 350 degrees.
Bake the cookies for 11-14 minutes. The edges should be lightly browned- don't overdo it or they will be crispy.
Remove them from the oven and let them cool slightly or enjoy them warm. Of course, don't forget the tall glass of cold milk- the best way to enjoy chocolate chip cookies.