There's nothing really secret about the recipe some of it I stole from my mother-in-law, some of it is just trial and error that worked out over the years. I finally wrote it down when the kids got old enough to leave home so that they could have the blueprint. I make it a bit differently every time.
We have several "secret recipes" some I haven't written down yet. After some five decades of cooking, I don't know what was my idea and what I took from another cook. I learn new tricks all the time. I can't teach what I do to everyone because I don't what it is that do.
Cooking is an art. The secret is there is no secret. It is all training, practice, and a bit of talent. I've said that wrong. If I compare cooking to painting-- anyone can be taught to smooth paint onto a flat surface, but once in a while someone comes along who can create a three dimensional view with the same paint on the same flat surface. In cooking, anyone can be taught the basics but sometimes there are people who can create substance from nothing. I'm not saying that I'm an artist in the kitchen (Grandma Moses) but I just do what I do based on instinct more than training.