- Melting a generous amount of butter before combining it with other ingredients gave the desired chewy texture. Since they were melting butter, they browned a portion of it to add nutty flavor.
- Using a bit more brown sugar than white sugar enhanced chewiness, while a combination of one egg and one egg yolk yielded supremely moist cookies.
- For the crisp edges and deep toffee flavor, they allowed the sugar to dissolve and rest in the melted butter. That meant setting aside the cookie dough for 10 minutes, and stirring several times, until the butter-sugar mixture resembled shiny frosting. Then, they added the flour and chips and shaped the dough into balls.