By and large, recipes can only be protected as trade secrets. Protecting trade secrets requires keeping the information confidential and only sharing it with people who owe you a duty of confidence, such as through a non-disclosure agreement. If you do not have any employment agreement, I do not know of a legal vehicle either of you could use to keep the other from using the recipes going forward.
Here is an example of a recipe being protected (note the confidentiality efforts): http://blogs.orrick.com/trade-secrets-watch/2013/10/31/halloween-edition-cookie-maker-gets-early-treat-when-court-protects-halloween-cookie-recipe-as-a-trade-secret-2/#more-492
Answered on Nov 07th, 2013 at 9:47 AM