The Alchemaster's Apprentice: A Culinary Tale from Zamonia by Optimus Yarnspinner

The fourth book in the beloved Zamonia series by Overlook's bestselling Walter Moers
The first three books set in Zamonia (the mythical land created by the genius of Moers, whose work has been compared to J. K. Rowling, Douglas Adams, and Shel Silverstein) have achieved raucous critical acclaim and created hundreds of thousands of die-hard fans everywhere. Now Moers returns with a fourth ?relentlessly whimsical? fantasy ("Library Journal").
When Echo the Crat's mistress dies, he is compelled to sign a contract with Ghoolion the Alchemaster. This fateful document gives Ghoolion the right to kill Echo at the next full moon and render his fat, which he hopes to brew into an immortality potion. But Ghoolion has not reckoned with Echo's talent for survival and his vast ability to make new friends.