Practically speaking, it is difficult to protect a cooking recipe because once copies of it have been sold, anyone who has a copy could conceivably make more copies and distribute it for free. Unfortunately, patenting a recipe is an uphill battle unless it involves a novel, non-obvious method of cooking (rather than simply a particular mix of ingredients), and a patent would be the only way to get a legal monopoly over using it. For this reason, many famous recipes (such as the formula for Coca-Cola) are treated as trade secrets rather than patented. You can also register copyright in the actual written document describing the recipe, which would make it illegal for others to copy it, but enforcing that copyright could be challenging. (Copyright registration is straightforward and can be done online for $35. See link below.)
Trade secret rights can be lost unless steps are taken to treat the recipe as a true secret, such as only disclosing it on a need-to-know basis. If you share it with restaurants, commercial bakeries, etc., it would be a good idea to ask them to sign a non-disclosure agreement before showing the recipe to them. You could register copyright in the written recipe, marking it confidential and with a copyright notice, and make a business out of selling licenses to use the recipe (as a trade secret) to businesses. The benefit of licensing rather than "selling" a trade secret is that a license permits the holder of the trade secret to impose conditions on how the information is used and under what circumstances.
I'm not sure whether you want to sell the RECIPE or the FOOD. As Mr. Johnson says, once you sell the recipe, it's almost impossible to keep the ingredients list from going further.
If it's a "family recipe" in the sense that your great-grandmother came up with it and handed it down through the generations, then you can't get a patent on it at all, since you're not the inventor (among other reasons).
If you put the recipe in a cookbook, the you can copyright the cookbook, but that still won't stop people who bought the book from telling their friends what the ingredients are.
Your best bet may be to treat the recipe as a trade secret. How do you keep a secret? Don't tell anybody. If you want to hire a baker or commercial kitchen to produce your product, then require them to sign an NDA before getting the recipe. You'll want to have a lawyer put together an NDA that will protect your interests adequately.
As my colleagues correctly pointed out, recipes are difficult to protect and get a monopoly on. Think about it ---do you know of any recipes you can't get versions of on the internet?
They generally aren't eligible for patents, because patents cover processes, not lists of ingredients.
Similarly, recipes aren't generally copyrightable, because copyrights cover creative expressions, and unless your particular expression of the recipe is a poem or written in calligraphy or as something literary or visual art, it can be copied by anyone, Even if your recipe is creatively expressed enough to be copyrightable, that would only protect from others copying that particular expression of the recipe, and not the list of ingredients and directions.
The recipe might be able to be protected as a trade secret, but it sounds like you've already disclosed it to your local businesses, and you can't do that with something you intend to perserve as a trade secret.
Instead of trying to simply protect the recipe itself, why not broaden your ambitions and create a business for yourself out of products made from the recipe? It's more work, but you can make and market the recipe yourself under your own trademark, e.g., as the Original Smith Family's Anza Cookie (or whatever TM you can come up with that's available, viable, catchy and fanciful). If you have a good product and you get it in the market first with some innovative advertising, you can create consumer "secondary meaning" so buyers recognize your TM as a source of your product, and it will hard for others to compete with you.
Once you create and use your TM with your product, you can apply for registration with the USPTO (or you can apply based on an "intent to use," without having used it yet. If you're successful in getting your TM registered, you get a presumption of it's validity and that will make it harder for anyone to infringe your TM. TMs require vigilant monitoring of your market, and it's basically "use it or lose it."
You should start by doing some reading on how to launch a small business, and how to use and get a TM. Then see an IP/business lawyer to help you organize your business and acquire and protect your IP.
Disclaimer: Please note that this answer does not constitute legal advice, and should not be relied on, since each state has different laws, each situation is fact specific, and it is impossible to evaluate a legal problem without a comprehensive consultation and review of all the facts and documents at issue. This answer does not create an attorney-client relationship.