Browning the butter is the entire upgrade. It takes five minutes and turns a good cookie into the kind people ask about — nutty, toffee-deep, with edges that shatter and centers that stay soft if you pull them at the right moment. The right moment is earlier than you think.
Chop the chocolate by hand instead of using chips. The shards melt into layers and the chunks make pools, and a cookie with both is doing more than a cookie with either.

