1Melt the butter in a nonstick skillet. Keep it on low heat and swirl it occasionally while watching the color. In the meantime, combine the sugars in a large-ish mixing bowl and the flour, baking soda, and salt in a separate, medium bowl.
2When the butter starts to brown (you can smell this happening, and I recommend using a spoon to kind of scoop up the liquid butter and check the color, since the nonstick skillet bottom is dark), watch carefully and remove from heat before it burns. Pour the butter into the sugars and stir to combine.
3Preheat the oven to 350° F. Line two half-sheets with parchment paper.
4Touch the butter-sugar mixture to make sure it’s just warm (not hot–if it’s hot, wait a couple minutes), then add the egg, egg yolk, and vanilla. Stir in the flour mixture, then add the chocolate chips. Stir well and stick the bowl in the freezer for ten minutes, or until cool to the touch.
5Use a #40 portion scoop/disher to plop the dough onto the prepared baking sheet two-inches apart. 12 cookies fit on a standard half-sheet. Bake for 12 minutes, and rotate the sheet half-way through. Remove from oven when edges are slightly (seriously, only slightly) brown and immediately transfer cookies to a wire rack to cool.
6Store cooled cookies in a container with the lid on loosely. Air-tight will make the cookies stale. So will leaving them out in the open. I don’t condone the use of plastic in general, but putting the cookies in a big Ziploc bag and leaving it un-zipped keeps them well, too.