I came across this many years ago and thought it may complement Yorkshire fried chicken. However, I really don't know how to make it. I'm thinking of starting with a base béchamel sauce but do I fry the onions, boil them or just add them raw? Is there anything else that I should add (in addition to seasoning)? Perhaps sliced mushrooms? I will likely serve the chicken with mashed potatoes and garden peas or shredded cabbage. Any ideas?