Step 2: Flour, A Rising Agent, and A Binding Agent
The rising agent or leavener most commonly used is either baking soda or baking powder. If you use baking soda, your recipe must include another acidic ingredient, like sour cream, lemon juice, or buttermilk. On the other hand, baking powder has its own built-in acid. Baking soda increases browning and spreading, resulting in a flatter cookie. Baking powder will give you a puffier cookie.
Binding agents are the liquid in the recipe that hold the cookie together. Examples of binding agents are eggs, milk, honey, and fruit juice. Cookies with more eggs will rise more and spread less. If you want a crispier cookie, you can replace a whole egg with just an egg white. Or, if you want a chewier cookie, you can replace a whole egg with just an egg yolk.