what i learned from america's test kitchen:
despite the recipe calling for "softened" butter, i melted it. well, ¾ of the butter was melted and then mixed with the rest of the butter. this does two things. it cools the melted butter and melts the remaining ¼. america's test kitchen actually melts the butter in a non-stick pan and browns it to bring out the nuttiness. i didn't do this, however.
the melted butter (to mix before the rest of the ingredients) makes the cookie crispy on the outside and chewy on the inside. after the butter and sugars are "creamed," let the mixture sit to allow the sugars to dissolve. when baked, this causes the sugars to caramelize rather than melt. i notice that the cookie is not as flat as the usual recipe i use. i guess i will have to test this out which means... more cookies.
the recipe calls for 2 2/3 cups of flour. i put in 2/3 cup of whole wheat flour to make it a little healthier which i'm sure gets canceled out anyway. my niece who was my guinea pig didn't notice, at all.