From Wikipedia, the free encyclopedia. Chicken Divan is a chicken casserole usually served with broccoli, almonds, and Mornay sauce. It was named after the place of its invention, the Divan Parisiennne Restaurant in the New York Chatham Hotel where it was served as the signature dish in the early twentieth century.ts creator, a chef named Lagasi, created it as part of a contest, winning a small amount of money and creating the hotel's signature dish. In French, the word divan refers to a meeting place or great hall, and thus the name was chosen to imply a kind of continental elegance.