Preheat the oven to 325 degrees F or 165 degrees C
Prepare a cookie sheet by lining it with parchment paper.
Cream the butter and two sugars until light and fluffy in the bowl of your stand mixer fitted with the paddle attachment.
Add the vanilla extract, then the egg, followed by the egg yolk.
Sift together the flour, baking soda, and salt and add it to the butter mixture with the mixer on low speed. Mix until just combined. (See notes)
Fold in the and chocolate chips.
Drop the dough on your prepared cookie sheet, using a 1 ¾-inch-diameter cookie dough scoop (or use a rounded tablespoon).
Wet your hands and flatten the dough slightly.
Bake for 15 minutes (See notes), remove from the oven and let cool slightly on the pan, then transfer to a wire rack to cool completely.
Enjoy!!