What's your "secret" ingredient?

I was watching a cooking show where they take a young woman who doesn't think she can cook but her mother can and have the mother make up some of the girl's favorite recipes. I saw one the other day where the mother was making meatballs and spagetti sauce. She put cinnamon in the sauce. They were Italian and lived somewhere in New York.

In some recipes, curry powder is my secret(ish) ingredient.