A dog's life - Cathy East Dubowski

When Harvey stops by Sabrina's house with Macdougal, the dog he's pet-sitting, he finds Sabrina elbow-deep in brownie batter. She's trying to bake like a normal teenager - without using her powers. But with some of her ingredients missing and her electric mixer on the blink, Sabrina decides to conjure up a little magical help.
Suddenly, Sabrina's mixing spell goes horribly haywire, bouncing into the dining room and zapping Harvey and Macdougal. Now Harvey's in canine chaos and his voice is coming out of the golden retriever's drooling jaws!
With the Quizmaster on her case and her best friend chasing cats, Sabrina's in the doghouse - unless she can find the trick that will get rid of Harvey's dog days for good!