Title to this book?

Question: Title to this book!?

The cover has a girl holding out a pink frosted cupcake!. The title goes something like "Devilishly blank" or something like that!.
Basically she goes to a boarding school and a new girl comes, turns out she is the devil, main protagonist's friend makes deal with her!. She trades places with her friend and outsmarts the "daemon" (she is apart of Hell Inc!., it works like a corporation, the more souls u get, the higher the placement on the pyramid/ladder)Www@QuestionHome@Com

Best Answer - Chosen by Asker:

Oh, I've read that book! Um!.!.I't's called!.!. your right, it's something about devil!. Let me check!. I kept a list of every book I've read this year!. Just a sec!.!.!.It's Devilish by Maureen Johnson!. Really good book!.Www@QuestionHome@Com

Found it! It's just called Devilish:
http://www!.amazon!.com/Devilish-Maureen-J!.!.!.Www@QuestionHome@Com