This is a bit confusing. I'm currently writing a cookbook, and a chef said he would send me one of his restaurant's recipes. When he did, it was in the form of a scan of the recipe as it was featured in another book. So clearly the recipe came from him and I have his permission to use it, but it also exists in this book. Do I cite the chef, or the book, or both for this?
Why are you so sure that the recipe came from him in the first place? Restaurants do use other people's recipes sometimes. You may not actually have permission to use it at all. Check.
Cite the book. That's the reference that anyone else can refer too.
It would be polite to mention the chef, either with the citation or in the acknowledgements. Do write him a personal letter of thanks; maybe even send him a free copy of your book.