From America's Test Kitchen Season 1: Cookie Jar Classics
Recipes for peanut butter cookies tend to fall into one of two categories: sweet and chewy with a mild peanut flavor, and sandy and crumbly with a strong peanut flavor. What we wanted, of course, was the best of both worlds—that is, cookies that were crisp on the edges and chewy in the center, with lots of peanut flavor.
First off, we had to determine the amount and type of sugar. Granulated sugar was necessary for crisp edges and chewy centers, while dark brown sugar enriched the peanut flavor. As for flour, too little resulted in an oily cookie, whereas too much made for dry cookies. Baking soda contributed to browning and amplified the peanut flavor and baking powder provided lift, making both leaveners necessary. Extra-crunchy peanut butter also helped the cookie rise and achieve a crisper edge and a softer center. But the best way to get the true peanut flavor we sought was to use peanuts and salt. Adding some roasted, salted peanuts, ground in a food processor, and then adding still more salt (directly to the batter as well in the form of salted rather than unsalted butter) produced a strong roasted nut flavor without sacrificing anything in terms of texture.
Makes approximately 3 dozen cookies
Bringing the butter, peanut butter, and eggs to room temperature makes it easier to blend the ingredients. Be sure to grind the peanuts, since whole, and even chopped peanuts tend to slip out of the dough. If using unsalted butter, increase salt to 1 teaspoon. Keep finished cookies refrigerated in airtight container. To restore just-baked chewiness, wrap a cookie in a sheet of paper towel and microwave for approximately 25 seconds. Cool before serving.