Chicken Casserole is a one-pot American chicken recipe made with chicken, vegetables, milk, butter and flour. Chicken Casserole is a heartwarming dish perfect for an appetite quenching dinner. Chicken is seared in a pan with butter. Garlic and mushrooms are added and sauteed for a few minutes. Flour is added to the mushrooms followed by milk. The sauce is seasoned with salt, pepper, chilli flakes, cheese and worcestershire sauce. Chicken, spinach and cherry tomatoes are added and mixed well. Chicken along with sauce is transfer to a baking dish and baked to perfection until cooked and the sauce has thickened. Chicken Casserole is best served piping hot.