One Of Life's Great Questions

Today we made Peanut Butter Cookies at work. As I was making the fork marks that make Peanut Butter Cookies recognizable the world over, I got to thinking. Who was the first person to put the fork marks on Peanut Butter Cookies? And why did they do it?

This kind of thing keeps me up at night. ok, so it doesn't but it sounded good. But I have wondered about this before. I even checked online, but not even Google could answer my question. 335,000 recipies for Peanut Butter Cookies, and not one of them (ok, not one of the first 20) could explain this.