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1
Adjust oven rack to middle position and heat oven to 375 degrees.
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2
Line 2 large (18- by 12- inch) baking sheets with parchment paper.
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3
Whisk flour and baking soda together in medium bowl; set aside.
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4
Heat 10 tablespoons butter in 10 inch skillet over medium-high heat until melted, about 2 minutes.
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5
Continue cooking, swirling pan constantly until butter is dark golden brown and has nutty aroma, 1 to 3 minutes.
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6
Remove skillet from heat and, using heatproof spatula, transfer browned butter to large heatproof bowl.
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7
Stir remaining 4 tablespoons butter into hot butter until completely melted.
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8
Add both sugars, salt, and vanilla to bowl with butter and whisk until fully incorporated.
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9
Add egg and yolk and whisk until mixture is smooth with no sugar lumps remaining, about 30 seconds.
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10
Let mixture stand 3 minutes, then whisk for 30 seconds.
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11
Repeat process of resting and whisking 2 more times until mixture is thick, smooth and shiny.
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12
Using rubber spatula or wooden spoon, stir in flour mixture until just combined, about 1 minute.
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13
Stir in chocolate chips and nuts (if using), giving dough final stir to ensure no flour pockets remain.
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14
Divide dough into 16 portions, each about 3 tablespoons (or use #24 cookie scoop).
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15
Arrange 2 inches apart on prepared baking sheets, 8 dough balls per sheet.
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16
(Smaller baking sheets can be used, but will require 3 batches.
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17
).
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18
Bake cookies 1 tray at a time until cookies are golden brown and still puffy, and edges have begun to set but centers are still soft, 10 to 14 minutes, rotating baking sheet halfway through baking.
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19
Transfer baking seet to wire rack; cool cookies completely before serving.
