Artifacts from the family of Col. Harland Sanders contained fried chicken recipes, but KFC has insisted the one with the correct 11 herbs and spices is kept secure in its headquarters.

KFC’s “Original Recipe” trademark, which it says is a secret blend of 11 herbs and spices, has long been part of the company’s branding. The blend is closely guarded, and the company calls it one of the most “iconic trade secrets in the food industry.” It first trademarked the phrase in 1984.

Church's Chicken has recently begun advertising some new chicken, bragging about the fact that they've gone back to the "original recipe." This is famously what KFC calls its fried chicken, in reference to Harland Sanders' original recipe.