Nonfiction book proposals (aside from memoirs) are different from fiction queries. While there's a query, it's a bit more cursory than what is written for fiction, and the proposal includes a table of contents, a market assessment (what is already out in the marketplace and how your book would be different), and a sample chapter or two, among other things. Typically, nonfiction books aren't expected to be written when you're querying because a publisher (an NF book might go directly to a potential publisher) might say, "no, don't need chapter 4 because of XY and Z." Perhaps the most important part is the competition analysis. It's better to be able to show that you have competitive books. It demonstrates that there there is an audience for the topic. It's also generally important -- especially for larger publishers -- that you have some qualifications for writing the book. Basically, a publisher might say, "that's a great idea. Why should you be the author?" This is where having an established platform, (e.g., well-traveled blog, history of magazine articles, engaged audience, etc.) become very important. Keep in mind that recipes are public domain, but the description surrounding them are not.