Ok so I've been looking for the damn book everywhere and can't find it. Reading comments on wowhead says it's been removed and cooking can be learned from trainers in any city. Like hell it can! I've been to Orgrimmar, Undecity, Shattrath and Dalaran and can't find anyone to learn Expert Cooking from.
So, WTF? WHERE!?
(sorry, but getting really pissed off after visiting so many places for nothing)
I leveled cooking 6 days ago, always went to the trainers... not sure why you can't see the next level.
There was no book for me, no need.
I just fished and cooked my way to 450 in a matter of days. Went to trainers to learn new recipes (had to buy some from vendors for like 30s... for fishing).