Flour plays a huge role when it comes to recipes. Depending on the ratio to other ingredients in the dough, flour makes cookies chewy or crispy or crumbly. For example, in a dry cookie dough, like shortbread, a high proportion of flour to the small amount of liquid in the butter produces a tender, crumbly texture. Also, cookies that need to hold their shape during baking, like biscotti, also have a high ratio of flour. In fluid-batter cookies like brownies, a lower proportion of flour to the amount of liquid results in a cakey or chewy texture. However, what you are looking for in a chocolate chip cookie falls in the middle, with the exact ratio depending on whether the baker wants a thick or thin, chewy or crumbly, or soft or crispy cookie.
Bleached or Unbleached:
Bleached and unbleached flour are pretty much interchangeable in cookie recipes, but the bleaching process alters protein structure, resulting in less gluten formation in doughs and batters made with bleached flour. For this reason, unbleached flour is a better choice where a slightly chewier texture is desired, which in this case you want that for a chocolate chip cookie.
Another option for baking is whole-grain flour, such as whole wheat. However, you don’t want to substitute no more than 30% of the flour in the recipe with whole-grain flour, because it makes a nuttier, heartier flavor. Finally, at higher ratios, whole-grain flours will make cookies denser, less chewy, and slightly gritty.