combine the cooked, chopped chicken with the sour cream,chicken soup, onion and green chilies. mix well. in a 13x9 baking dish, put a small amount of the mix on the bottom so the shells do not stick. cover bottom of dish with shells then top with (about 1/3 of)mixture. top the mixture with cheese, the repeat layers until mix is gone. top with shells or doritos chips and top with cheddar cheese. bake at 350 degrees for 30-35 minutes or until mixture is hot and bubbly and cheese is melted.