Chocolate Chip Cookie Bars (Cook’s Illustrated)

My go-to favorite cookbook series are the Cook’s Illustrated books. Also known as American’s Test Kitchen, as the name implies, these books are all about finding the very best version of every recipe they tackle and every recipe in their many books, is can’t fail and totally delish! 


For this chocolate chip cookie recipe, we wanted to duplicate, at home, the big, delicious, chewy chocolate chip cookies bought in trendy specialty cookie shops. One key element in developing this chocolate chip cookie recipe was melting the butter, which gave the cookies a chewier texture. After numerous tests varying the type of flour and the proportion of flour to butter, and sifting and not sifting, we decided that the best cookie resulted from unsifted bleached all-purpose flour, which has a lower protein content than unbleached. Also, the problem of the cookies hardening after several hours was eliminated by the addition of a single egg yolk; the added fat acted as a tenderizer. (less)


You can substitute white, milk chocolate, or peanut butter chips for the semi- or bittersweet chips called for in the recipe. In addition to chips, you can flavor the dough with 1 cup of nuts, raisins, or shredded coconut.


2 1/8

cups bleached all-purpose flour (10 1/2 ounces)


teaspoon table salt


teaspoon baking soda


tablespoons unsalted butter (1 1/2 sticks), melted and cooled slightly


cup light brown sugar (7 ounces)


cup granulated sugar (3 1/2 ounces)


large egg


large egg yolk


teaspoons vanilla extract


cups chocolate chips or chunks (semi or bittersweet)


  1. 1. Heat oven to 325 degrees. Adjust oven rack to lower-middle position. Cut 18-inch length foil and fold lengthwise to 8-inch width. Fit foil into length of 13 by 9-inch baking pan, pushing it into corners and up sides of pan; allow excess to overhang pan edges. Cut 14-inch length foil and fit into width of baking pan in same manner, perpendicular to first sheet (if using extra-wide foil, fold second sheet lengthwise to 12-inch width). Spray foil-lined pan with nonstick cooking spray.
  2. 2. Mix flour, salt, and baking soda together in medium bowl; set aside.
  3. 3. Whisk melted butter and sugars in medium large bowl until combined. Add egg, egg yolk, and vanilla and mix well. Using rubber spatula, fold dry ingredients into egg mixture until just combined; do not overmix. Fold in chips and turn batter into prepared pan, smoothing top with spatula.
  4. 4. Bake until top is light golden brown, slightly firm to the touch, and edges start pulling away from sides of pan, 27 to 30 minutes. Cool on wire rack to room temperature. Remove bars from pan by lifting foil overhang and transfer to cutting board. Cut into 2-inch squares and serve.



  • 1. Line the baking pan with two sheets of foil placed perpendicular.
    • 2. Use the foil handles to lift the cooked brownies or bar cookies from the pan.