Cream the butter, brown sugar, granulated sugar and vanilla on medium speed until light and creamy, about 2 minutes.

Add the eggs and egg yolk one at a time, mixing until each is fully incorporated before adding the next one.

In a separate bowl, combine the flour, baking soda, and salt and stir together. Add half of the flour mixture to the creamed mixture and beat just until combined. Add the rest of the flour and mix until the flour is blended in.

Add the chocolate chips and mix them in by hand with a rubber spatula. Chill dough for 1 hour or up to two days.

Using a 1 ½ tablespoon cookie scoop, scoop dough into balls on a parchment-lined cookie sheet. Chill until ready to bake, at least one hour.

When ready to bake, preheat oven to 350°F. Bake for 12 to 14 minutes or until very lightly browned. (In my oven, these are perfect at 12 minutes and 20 seconds but every oven is different.)

Let cool on the baking sheet for 2 minutes and then remove to a cooling rack. Cool completely and store at room temperature for up to 5 days (if they last that long!).