I did this at one point, so that I could send a copy of all my recipes to my mother's Kindle, but it's several years out-of-date at this point, and to be honest I've forgotten how I did it.
I store all of my recipes in
Copy Me That (which I originally got into for the easy recipe scraping from websites, not so much for the organization), which I
believe also has an export to HTML option. Most likely I simply exported everything to HTML then did a basic cobbled-together EPUB using Calibre's ebook editing tools.
It's probably not a good future-proof technique for a frequently-changing recipe book. I'm constantly adding new ones and deleting ones we didn't like or don't cook very often anymore, so, perhaps the exercise of creating a v2 will make me come up with a more easily iterable solution rather than doing a mass dump-and-recreate-from-scratch operation every time.