Cooking en casserole is perfectly suited to seafood. Minimal baking time (about half an hour) brings out the unique flavor of fish and shellfish while preserving their delicate textures. In our first recipe, fresh creamed spinach blankets a cod fillet baked with a cheddar-breadcrumb topping. In the Sicilian option, a quick Mediterranean sweet-and-savory vegetable sauté is spooned over swordfish steaks and baked to perfection. Craving shellfish? Our subtly curried crab with mushrooms, bell pepper, and chives is ideal for brunch or dinner.
Treat these updated seafood casseroles with care. Because seafood overcooks in an instant, the dishes are not great candidates for making ahead and freezing. But they are a fresh and simple dinner solution: Just assemble, pop in the oven, and carry to the table to savor at their peak.
• Glass and ceramic (earthenware) dishes work best for casserole cooking because they heat up quickly and evenly. If you substitute a metal baking pan, the casserole usually cooks more slowly, so you may have to increase the oven temperature by 25 degrees to compensate.
• Always start with the freshest seafood available and pat it dry. If you use individual steaks or fillets, select pieces that are at least 1 inch thick. If a single fillet from a large fish tapers to a thin end, fold the thin end under to help the fillet cook uniformly.
• If the fillet in the casserole is thick, let it sit at room temperature while you prepare the other ingredients for the dish. It will cook more quickly.
• Thick fillets or steaks, especially if covered with a sauce or topping, can take from 12 to 15 minutes of baking time per inch. To check for doneness, cut into the fillet at the thickest part to see if it's opaque inside and pulls apart with little resistance.
• Casserole recipes calling for fully or partially cooked seafood or fish need only enough time in the oven to get hot, so an instant-read thermometer comes in handy. If the middle of the casserole registers 160˚, it's done.
• If you're making a casserole with cooked seafood that's added to a sauce, heat the sauce separately, stir in cold, cooked fish, and then assemble the dish. This will speed up the time in the oven and keep the fish from disintegrating.
• Don't cook fish until it flakes easily―by that point, the fish has given up all of its juices, rendering it dry and leaving a lot of water in the dish. If this occurs, spoon the juices back over the fish when serving.
• Remember, the casserole will continue cooking once it's pulled from the oven, so it's better to take it out sooner rather than later.