A broccoli cauliflower casserole tends to simply refer to any dish that is prepared with these two vegetables and is baked in a single container prior to serving. There are many different ways in which this type of dish can be prepared, though the two vegetables are usually at least partially cooked prior to baking. One common additional ingredient in a broccoli cauliflower casserole is a sauce. This type of casserole frequently has some type of crunchy or crispy element, such as bread crumbs, crushed crackers, or fried onions.
The basic idea behind a broccoli cauliflower casserole is the creation of a single dish that includes both types of vegetables and can be fairly easily prepared. A number of different recipes exist for this type of casserole, which can be found in numerous cookbooks. All of these recipes, however, usually call for the broccoli and cauliflower to be at least partially cooked prior to baking, usually by boiling them briefly. This serves to help tenderize the vegetables and allows them to finish cooking in the oven without overcooking the casserole. Other ingredients like cooked rice or sautéed onions can be added to these partially cooked vegetables.
One important element that most broccoli cauliflower casserole recipes include is some type of sauce. This is usually made separately, often as a simple cream sauce made from a roux of flour and butter, to which milk or cream is added. Shredded cheese is stirred into the sauce and melts down to a thick, cheesy consistency. This sauce is then poured over the vegetables in the broccoli cauliflower casserole, or they can be added to the sauce and tossed together to coat them.
The saucy mixture for the broccoli cauliflower casserole is poured into a large dish, usually called a casserole dish. Some type of crispy ingredient is then frequently added to the mixture, to ensure that it has a more appealing and diverse texture when eaten. This can include ingredients like bread crumbs that are either plain or lightly sautéed, crushed up salty crackers, or fried onions sprinkled over the casserole.
Once these ingredients are all together, then the broccoli cauliflower casserole is baked in an oven. This allows the vegetables to finish cooking through, to ensure they are not hard or crunchy, and lets the sauce better disperse through the dish. During baking, the crispy topping usually becomes slightly crispier and can cook to a light, golden brown before serving.