Jane, I worked it out like this:

Unadventurous chef is a person who would probably stick to boiling things in a pot; no frying or roasting or searing, just boiling.

Book for the unadventurous = pot boiler. Not a literary work, just an easy read designed to appeal to readers who aren’t interested in a challenging work.

Cookery could be described at its most basic as being pot boiling… chef at its most basic is a pot boiler… and it all slid nicely into place for me in my (sorry, Sherlock!) mind palace.