Recipe protection is rare but possible.
A recipe normally combines a list of ingredients with preparation instructions. It can result in a very unusual or original dish. When a recipe is copied, the author can get very upset that his or her unique and valuable work product is being ripped off.
Putting aside the morality of such unauthorized copying, the legal remedies are limited.
The modern view is that individual recipes are not copyrightable, even though some older cases going as far back as 1892 formerly held otherwise. A list of ingredients is factual, and the procedures for combining and processing them likewise are factual. Facts are not copyrightable because they are not considered to be original creative works of authorship.
How about cookbooks? Although the selection and arrangement of materials can be a copyrightable compilation, this is severely limited when it applies to factual material. So either a compilation of recipes is not copyrightable, or is strictly limited to a substantially identical selection and arrangement.
The Copyright Law also preempts state law seeking to protect rights that are equivalent to copyright. So attempts to assert causes of action such as conversion, negligence, quasi-contract, or prima-facie tort failed because they essentially were complaining about copying which is within the scope of the Copyright Law.
Nevertheless, there are some steps you might take to get legal protection for your recipes. It is possible to embellish a recipe with expressive elements such as original illustrations or layout; creative narrative about the sensual effects of the dish; hints on place settings or appropriate music; suggestions about the presentation of the dish or a wine to pair with it; tales about historic or ethnic origin; musings about the spiritual nature of cooking; or personal reminiscences associated with the dish.
Such additional elements might be protected under copyright even if the recipe itself is not so protected. Each copy of such an embellished recipe may have a copyright notice such as © [date of first publication] [name of owner]. However, this is not a requirement for copyright protection.
Copyright normally would not prevent someone else from actually preparing the dish, from making a photograph of the dish, or from describing the recipe without using the same expressive elements as you used.
If a particular recipe has been kept secret, it can be protected from theft. Think of the Coca-Cola formula. This involves limiting access to just a few people who have a confidentiality obligation or have signed a non-disclosure agreement. Visitors to your facilities also should be asked to sign a confidentiality agreement. In addition, it would be desirable to put a notice on each copy if the recipe stating something like “Confidential trade secret. Not for publication. All rights reserved.”
Of course, trade secret protection will not prevent anyone from reverse engineering the dish to the extent they can. And once the recipe has been disclosed to anyone who does not have a confidentiality obligation, it loses its trade secret protection.
The unique way the finished dish looks might be considered a form of trade dress protected as a trademark to the extent that it has become uniquely identified as indicating a dish from you. However, one court considered a dish that was meant to be consumed as being too ephemeral for trade dress protection.
The best way to protect a recipe may be as a trade secret. In some cases, limited copyright rights can be asserted. But, in general, recipes are not protectable.