Casseroles are very popular because they are usually easy to put together and can be prepared in just one pan. This makes them easy to take along and minimizes clean up. Casseroles are generally a one-dish meal, but it can also be considered a casserole if made in a skillet. Many believe that a casserole is always baked in the oven, but I disagree. A casserole to me is a one pan or one dish meal!