Serves 4-6.

Season the pork loin with salt and pepper. Place the slices of pancetta on a work surface, put the roast over the pancetta, and wrap the pancetta around the pork. Tie the roast securely with string, and secure the sprigs of rosemary beneath the strings.

Heat the oil in a large, heavy casserole over medium heat. Add the roast and brown it very lightly all around, about 2 minutes. Keep turning the meat, to avoid burning the rosemary. When the roast has a pale, golden color, turn the heat off under the casserole and add the potatoes and the garlic. Season the potatoes with salt and pepper and mix them with the oil.

Place the casserole in the oven and bake 40-45 minutes at 350°. Baste the roast with its pan juices a few times during cooking. The roast is done when a meat thermometer in the center of the thickest part reads about 150° and the juices run clear or barely pink when the meat is pierced.

Transfer the roast to a cutting board and let it settle 5-10 minutes. Meanwhile, tilt the casserole slightly away from you and remove as much fat as possible. Remove the string from the roast, slice the meat, and serve with the potatoes, garlic, and a bit of pan juices.