My cat has pancreatitis and won't eat z/d. What food can he eat?

I am assuming your vet suspects Henry has a chicken intolerance that may be contributing to the pancreatitis bouts.

Hill's z/d and Royal Canin HP are what are called "hydrolyzed protein diets." These diets are designed such that the proteins have been processed to be broken down to such small pieces that the body won't recognize them as something that could mount an allergic or intolerance response.

If your cat won't eat these foods THAT'S OK! There are other appropriate foods available, because another possible approach to concerns for allergies and intolerances is to use a different protein altogether; these are called "novel protein diets." There are some high quality foods available that may be very helpful; including this diet-- Royal Canin PR (protein source is peas and rabbit):
https://www.royalcanin.com/products/royal-canin-veterinary-diet-feline-selected-protein-adult-pr-dry-cat-food-8.8-lb-bag/762188
Or Hills d/d (rather than z/d): protein source is peas and venison)
https://www.hillspet.com/cat-food/pd-dd-feline-venison-and-green-pea-formula-dry

If you do decide to cook for him, check out the site balanceit.com which will help you with a recipe.

While diet can be a factor with pancreatitis, and we definitely worry about a high fat diet predisposing to the condition, no one knows exactly why some cats develop pancreatitis. Here is some good information on pancreatitis is cats.

https://www2.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/feline-pancreatitis-serious

I hope that helps you!! Thanks for asking PetCoach!