While casserole is a French word denoting a certain type of baking dish, as with most bastardized foreign words in English, we've altered the meaning to more generally refer the contents of the said dish. I for one am a fan. They are easy to make. They are versatile and forgiving. And they at there heart, they are made up of 3 parts with an optional 4th for the fancy ones.
Part 1 is the starch. You can choose, noodles/pasta, rice or potatoes
Part 2 is the veggie/meat
Part 3 is the filler. Again roux, cream, cheese, condensed soup, etc...
Part 4 could be a topping. Bread crumbs, onion crunch, cheese or even potato chips
This one I made with
Part 1: Egg Noodles
Part 2: Chicken (ALWAYS PRE-COOK THE MEAT), peas, baby portobello mushrooms and carrots
Part 3: A combination of Cream of Onion soup (condensed), sour cream, heavy whipping cream, and mild cheddar cheese
and I opted for a Part 4, those French's crunch onion thingies.
Once assembled backed at 300˚ for 55 minutes.