1Place oven rack to middle position and heat oven to 375 degrees. Line two large baking sheets with parchment paper.
2Whisk flour and baking soda together in medium bowl and set aside.
3Heat 10 tablespoons butter in a skillet over medium high heat until melted. Continue cooking, swirling pan constantly until butter is dark golden brown.
4Remove skillet from heat and transfer browned butter to a large heatproof bowl. Stir remaining four tablespoons butter into hot butter until completely melted. Add both sugars salt and vanilla to bowl with butter and whisk until fully incorporated. Add egg and yolk and whisk until mixture is smooth with no sugar lumps remaining. Let mixture stand three minutes then whisk for 30 seconds. Repeat process of resting and whisking two more times until mixture is smooth and shiny.
5Using a wooden spoon or rubber spatula stir in flour mixture until just combined. Stir in chocolate chips giving dough a final stir to make sure there are no flour pockets.
6Using a small melon scooper arrange dough about 2 inches apart on parchment baking sheets. Bake cookies one tray at a time until cookies are golden brown and still puffy and edges have begun to set about 10-14 minutes. Rotate the tray half way through cooking time. Take the tray out and let cookies set a little before you remove them.