Butter: Cut the smaller division of butter into one-tablespoon chunks, and place in a heat-proof bowl. Place the remaining butter in a skillet and heat at medium-high until melted. Continue heating, swirling often, until the butter is dark golden brown and has a nutty aroma; this will take several minutes.

Meanwhile: Adjust oven rack to middle position and heat to 375°. Line large baking sheets with parchment paper (2 for single recipe)

In four separate bowls, prep the following:

• Whisk flour and baking soda together.
• Measure both sugars, salt and vanilla.
• Eggs in another bowl.
• Chips and nuts in the final bowl.

When butter is ready: Pour on top of the separated cold butter, and stir until all butter is completely melted. Add sugar-bowl contents to butter, and stir until completely melted. Add eggs to batter and whisk until mixture is smooth, about 30 seconds.

Let mixture stand 3 minutes, then whisk 30 seconds; repeat 2 more times. Batter should be thick, smooth and shiny.

Use rubber spatula to stir in flour mixture, until just combined. Stir in chips and nuts.

Use cookie scoop and arrange cookies 2" apart on parchment. Bake sheets one at a time (this is important!), for 10–14 minutes, rotating pan halfway through. The cookies are done when golden brown and still puffy, and edges have begun to set but centers are still soft. Place pan on rack to cool.