thinly sliced IN A LARGE, HEAVY oven-proof skillet, heat the oil until hot and almost smoking. Add the chicken breasts, turn back down to medium-high heat and saute until lightly browned, about 3 minutes. Season with salt and pepper. Turn and cook the second side for 1 minute. Remove the breasts, let them cool slightly, then slice into a fan. Return the chicken to the pan, pour over the marinara or spaghetti sauce, sprinkle on the oregano, place the mozzarella slices on top. Turn on your broiler and adjust the rack to 15 cm from the heat. Run under the broiler until the cheese is hot and bubbling. Serve at once with boiled orzo pasta.