I don't have a recipe I use every time- it's just what ever happens to be around.
In my opinion do not use chicken breast, it's too dry for slow cooking use thighs/drumsticks.
The liquid bit can be stock, cider, wine or tins of tomatoes depending on what you have going.
I do one with celery, onions, bacon and mushrooms cooked in stock. I add any left over cream if I have some but don't worry if I don't. Sometimes it's crusty bread or mash. I have also used creme fraiche instead of cream.
I have another with chorizo, rice, peppers, tomatoes and peas. I bung in rice with this
Another with carrots, onions, celery, pots and then stir fry cabbage to go on the side.
The beauty of the chicken casserole is it is never the same and uses up a load of leftover bits of veg.