Preheat oven to 375 degrees and line two baking sheets with parchment paper.
Separate the butter into 10 tablespoons and 4 tablespoon pieces. Cut the butter into small pieces so that it can melt faster. Set the 4 tablespoons aside.
Whisk the flour and baking soda together in a medium bowl; set aside.
Heat the 10 tablespoons of butter in a medium skillet over medium-high heat until melted. Once the butter is melted, continuously swirl the pan until the butter is browned and has a nutty aroma. This should take around 1 to 2 minutes. Keep an eye on the butter it turns brown really quick!
Transfer the browned butter to a large glass bowl. Add the remaining 4 tablespoons butter and stir until completely melted.
Add the sugars, salt, and vanilla and whisk to combine.
Set a timer for 3 minutes and 30 seconds. Add the egg and egg yolk and start the timer. Whisk for the first 30 seconds and then let the mixture sit for 3 minutes. Repeat this process two times.
Fold in the flour mixture and gently stir until no flour lumps are visible.
Add in the chocolate chips and stir.
Divide dough into balls, about 3 tablespoons. *See my note about cookie scoops below. Place them on the prepared cookie sheets.
Bake for 10 minutes, one baking sheet at a time in the preheated oven, until edges are golden brown and cookies have just started to set. Rotate the baking sheet halfway through the cooking time.
Allow to cool slightly, then transfer the cookies to a wire rack to cool completely.
Notes
I recommend using a stainless steel pan to brown the butter in. This way you can see when the butter is starting to brown. If you only have a non-stick skillet, just keep a very close eye on the butter as it will be harder to see when the butter turns brown.The whisking and resting process is really important to develop the flavor of the cookies, get the right consistency, and allow the sugars to dissolve completely.I use two cookie scoops for this recipe depending on what size of cookie I want.OXO Good Grips Cookie Scoop, Medium, Stainless SteelOXO Good Grips Cookie Scoop, Small, Stainless SteelThese cookies can be made, shaped into balls and then frozen. Bake following the instructions from step 11 at 375 degrees, after the dough, has thawed for around 10 minutes.Adapted from America’s Test Kitchen.