How do I make a chicken casserole?
Put one very large chicken breast quarter (for one person, obviously) into a casserole dish.
Fumble around in the back of the kitchen cupboard for a tin/packet of soup that looks like it might go well with chicken. (Cream of chicken works well but it's rather too obvious a choice. Cream of mushroom is possibly better. Chicken and leek soup is really nice in a casserole. Mulligatawny is an unusual choice but it works well if a spicy result is required).
Find some vegetables that go well with the choice of soup (or rush down the Co-op to buy some). Mushrooms work well with most soup choices but possibly not with mulligatawny. (Red and green peppers might go well there). Leeks, or even celery, might be worth a try alongside the mushrooms.
Add chosen veg and soup to the casserole dish, possibly laying slices of potato on the top, and put it in a really low oven (Gas Mark 1 or 2) for several hours. (It makes little difference whether it's 3 hours or 6 hours; it still works!). The flesh will simply fall away from the bone, resulting in a superb casserole. (If you've put potato slices on top, there's possibly no need for any other accompaniments but broccoli or cauliflower go well with mushroom/leek bases, whereas carrots and mustard mash go well with a spicier base).