What's the exact role of eggs in a cookie, and how does altering the ratio of yolks and whites and the way you incorporate them affect the result? I decided to find out in a series of controlled experiments. To tackle the entire world of cookies seemed like an exercise in futility, so I limited testing to my Soft and Chewy Sugar Cookies, figuring that the information I gleaned could be extrapolated into general rules for other cookies, too.
