Sorcery and Cecelia or the Enchanted Chocolate Pot: Being the Correspondence of Two Young Ladies of Quality Regarding Various Magical Scandals in Lond - Patricia C. Wrede

A great deal is happening in London this season.
For starters, there's the witch who tried to poison Kate at Sir Hilary's induction into the Royal College of Wizards. (Since when does hot chocolate burn a hole straight through one's dress?!)
Then there's Dorothea. Is it a spell that's made her the toast of the town--or could it possibly have something to do with the charm-bag under Oliver's bed?
And speaking of Oliver, just how long can Cecelia and Kate make excuses for him? Ever since he was turned into a tree, he hasn't bothered to tell anyone where he is!
The girls might think it all a magical nightmare . . . if only they weren't having so much fun.