A well-planned casserole can be a culinary triumph. Too often, however, a casserole consists of nondescript leftovers and bland sauce, or fillers such as rice and potatoes are used so heavily that meat appears only as a surprise. Another sort of casserole fiasco is a few pieces of vegetable or meat afloat in a pasty sauce. To avoid this, combine three parts solids with one part sauce. If the sauce is thin, use just enough to keep the main ingredients moist.
Casserole ingredients are usually cooked, cut into bite-size pieces, then mixed with a sauce and turned into a well-greased baking dish. Or solid ingredients and sauce can be layered into the baking dish, ending with the sauce. Fish, pasta, and vegetables should be slightly undercooked to prevent overcooking in the heating. Leave ‘/z inch of bubble-up space at the top of the casserole to prevent sauce from spilling over. For flavor and color sprinkle shredded cheese. buttered crumbs, or paprika on top just before baking. Or cover the casserole with biscuit or corn bread dough.
Preheat the oven to 350F or 375F. Place the casserole just below the center of the oven. Bake uncovered, unless the recipe specifies a cover, 30 to 45 minutes. It’s done when the sauce bubbles lazily at the edges and a spatula inserted in the center releases a puff of steam. If you’re not serving the casserole right away, cover it to keep it warm and prevent drying.
Casseroles can be assembled in advance, refrigerated or frozen, and whisked into the oven (don’t thaw a frozen one first). But plan ahead; a casserole that is frozen or very cold requires at least twice the baking time as a freshly made one. Fish, poultry, meat, pasta, rice, and vegetables freeze and reheat well. Avoid freezing potatoes; they tend to get watery.