I'd recommend distracting her. You may have to get good and silly to get her to forget about her cookie, but it almost seems that you don't have much of a choice since she didn't want the new cookie you offered her. And be warned that distraction may not work. She's a young toddler and is entering the world of tantrums and runaway emotions, where it's not uncommon to sob as if the world were ending over things that don't go just right for her. At that age (and to this day) I'd try distraction and keep trying it every so often while Tyler bawled, but if he clearly wanted no part of it, then I'd ride it out and let him have his cry. If you haven't read Tracy's toddler book yet, you might consider it...I started using some of those techniques around that age and still do.