Created in a Rhode Island casino near the turn of the 20th century, clams casino is a baked clam dish that serves the shellfish with a topping similar to a stuffed clam mixture. Often confused with stuffed clams, clams casino bakes the whole clam in the half shell instead of chopping the meat and combining it with the other ingredients. Additionally, this dish generally uses little or no bread crumbs. Clams casino is often baked on a bed of rock salt and is normally served as an appetizer.
Any type of clams can be used for clams casino, but either littleneck or cherrystone clams are normally selected. These are the smallest two varieties of commercially sold clams other than countnecks. The clams are shucked before used and may be completely removed from their shells so the shells can be more thoroughly washed. The top shell is discarded and the bottom is retained. Each intact clam is placed in the bottom half of the shell and arranged on a baking sheet or in a baking dish, which is usually first filled with rock salt.
Although the vegetables and other seasonings vary considerably in the topping, bacon, garlic, and butter are nearly always present. Fancier versions may use pancetta, a type of seasoned Italian bacon. Cheese, normally Parmesan, is also usually added. Vegetable choices include celery, green or yellow onions, bell peppers, and shallots.
Seasonings, such as oregano, paprika, or basil may be included, and salt and pepper are often added to taste. Liquid flavorings, most commonly dry white wine or lemon juice, are also frequently found in clams casino. Dried bread crumbs may be included in some versions but are usually added in small amounts so as not to overwhelm the other flavors of the dish. Extra virgin olive oil is sometimes included to top the dish directly before it is baked.
The filling for clams casino is made by cooking the bacon until it is crispy. The oil and butter are heated together in a pan, usually the same pan in which the bacon was cooked, and the vegetables and spices are sauteed. If wine is included, it is added after the vegetables have briefly cooked and the mixture is reduced. Any other ingredients are added at that time, and then the mixture can be spooned over the arranged clams. Clams casino is normally cooked at a very high temperature for a short time.