Orata is a type of bream with very fine flesh - snapper is an excellent substitute, and salmon, too, stands up well to this treatment, but you could also adapt this to thick steaks of swordfish or halibut, or to thick fillets of haddock or similar fish.
1 whole snapper or salmon, weighing at least 3 pounds
or 2 1/2 pounds 1-inch-thick halibut
or swordfish steaks
or 2 pounds plump haddock or cod fillets
1/2 cup extra virgin olive oil
3 garlic cloves
1/2 cup flat-leaf parsley leaves
4 medium russet potatoes, peeled and sliced about 1/4 inch thick
3 tablespoons freshly grated pecorino or Parmigiano-Reggiano cheese
Salt and freshly ground black pepper as desired
Oven-proof dish or pan large enough to hold fish and potatoes.
PREHEAT the oven to 400 degrees F.
RINSE the whole fish inside and out, scale it if necessary, pat dry with paper towels, and set aside. Use about 2 tablespoons of the oil to brush liberally the bottom and sides of a rectangular oven dish large enough to hold the fish.
CHOP the garlic and parsley together until they are minced very fine. In a bowl, mix the garlic and parsley with about 1/4 cup of the olive oil to make a loose paste. Toss the potato slices in this mixture to cover thoroughly.
ARRANGE about half the potatoes in the bottom of the dish, overlapping if necessary and spreading them out to distribute them evenly. Sprinkle with half the grated cheese. Add salt, if desired, and plenty of pepper. Now set the fish on the potato layer and cover with the remaining potatoes and grated cheese. Add more salt and pepper, and drizzle the remaining 2 tablespoons of olive oil over the top. Bake for about 40 minutes, or until the fish and potatoes are thoroughly cooked.
VARIATION: If you wish to make this with fish steaks or fillets, the roasting time will be much shorter - 10 minutes should be plenty. In that case, to avoid under-done potatoes, parboil the potato slices for about 10 minutes in rapidly boiling water before you mix them with the garlic-parsley-oil paste and assemble the ingredients.
A similar dish can be made with seppie ripiene, stuffed squid. Place slices of potato in the bottom of an oiled oven dish, as above, sprinkling with cheese and 1 tablespoon of dry bread crumbs, as well as salt and pepper. Place the stuffed calamari and their tentacles on top of the potatoes, cover with more potatoes, cheese, and bread crumbs, then pour on 1/4 cup extra virgin olive oil and 1/2 cup dry white wine. Bake in a preheated 400 degrees F. oven for about 1 hour.