A casserole (French: diminutive of casse, from Provencal cassa 'pan') is a large, deep pan used both in the oven and as a serving vessel. The word is also used for the food cooked and served in such a vessel, and, if so, the cookware itself is called a "casserole dish" or "casserole pan". "Casserole" should not be confused with the word cacerola, which is Spanish for "cooking pot".
Baked dishes have existed for thousands of years. Early casserole recipes consisted of rice that was pounded, pressed, and filled with a savoury mixture of meats such as chicken or sweetmeats. Some time around the 1870s this sense of casserole seems to have taken its current sense. Cooking in earthenware containers has always been common in most cultures, but the idea of casserole cooking as a one-dish meal became popular in the United States in the twentieth century, especially in the 1950s when new forms of lightweight metal and glass cookware appeared on the market. By the 1970s casseroles took on a less-than sophisticated image.
In the United States and continental Europe, casseroles usually consist of: pieces of meat (such as chicken or ground meat) or fish (such as tuna), various chopped vegetables, a starchy binder (such as flour, potato or pasta), and often a crunchy or cheesy topping. Liquids are released from the meat and vegetables during cooking, and further liquid in the form of stock, wine, beer (for example lapin a la Gueuze), gin, cider, vegetable juice, or even water may be added when the dish is assembled. Casseroles are usually cooked slowly in the oven, often uncovered. They may be served as a main course or side dish, and, conveniently, may be served in the vessel in which they were cooked.
In Commonwealth countries like the United Kingdom, Australia, and New Zealand, a casserole is named after its dish, rather than its contents; casseroles in these countries are very similar to stews. The difference is that once the meat and vegetables are browned on top of the stove, they are then cooked in liquid in a closed dish in the oven, producing meat that is tender and juicy, from long, slow cooking. The heat is indirect, so there is less chance of burning than on the stove.
Examples of casserole include: ragout (French), Lancashire hotpot (English), cassoulet (French), moussaka (Greek), shepherd's pie (UK), timballo (Italian), green bean casserole (US), and carbonnade (Belgian). As previously noted, a distinction can be made between casseroles and stews: stewing is a cooking process whereby heat is applied to the bottom of the cooking vessel (typically over a fire or on a stove), whereas casserole is generally baked in an oven, where heat circulates all around the cooking vessel. Similarly compared, casseroles may be cooked covered or uncovered, while braises are typically covered to prevent evaporation.