Adjust oven rack to middle position and heat oven to 375 degrees. Line 2 large baking sheets with parchment paper. Whisk flour and baking soda together in medium bowl; set aside.
Heat 10 tablespoons butter in a sauce pan over medium-high heat until melted, about 2 minutes. Continue cooking, swirling pan constantly until butter is dark golden brown and has nutty aroma, 1 to 3 minutes. Remove from heat and transfer browned butter to large heatproof bowl. Stir remaining 4 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, about 30 seconds. Let mixture stand 3 minutes, then whisk for 30 seconds. Repeat process of resting and whisking 2 more times until mixture is thick, smooth and shiny. Using rubber spatula or wooden spoon, stir in flour mixture until just combined, about 1 minute. Stir in chocolate chips.
Divide dough into 16 portions, each about 3 tablespoons (or use cookie scoop). Arrange 2 inches apart on prepared baking sheets and bake for about 8 minutes or until dark golden on the edges and just barely set in the middle but puffed up. Rotate sheets 1/2 way through. Baking time is hugely dependent on your oven, so check early and adjust baking time accordingly.