Step 1Bring a large pot of water to a simmer over medium-low heat. Pour the oil into a large metal bowl just large enough to sit over the simmering water without letting the bottom touch. Add the lamb to make sure the oil level is high enough to cover the meat. Then, using tongs, remove the meat and add the rosemary, shallots, bay leaves and garlic to the oil. Gently heat the oil to 135 degrees on a frying thermometer. Make sure the oil hovers between 135 and 140 degrees, as this will ensure that the meat is cooked to medium-rare.
Step 2Season the lamb heavily with kosher salt and pepper, and completely submerge the meat in the warm oil. The temperature of the fat will drop. Using the tongs to rotate the meat occasionally, poach for an hour or more. As long as the temperature of the oil stays below 140 degrees, the meat won't overcook. Check the temperature of the meat often to make sure it remains constant.
Step 3When ready to serve, use the tongs to remove the lamb from the pan, allowing the excess oil to drip off. Season it well with kosher salt and pepper. Place a large saute pan over medium-high heat and, when hot, coat with 2 tablespoons of the oil. Add the lamb and sear both sides until well browned. (At this point the meat is already cooked through from the poaching; you just want a slight crust on the outside.)
Step 4Transfer the lamb to a cutting board and let rest for at least 10 minutes. Carve into chops, season lightly with Maldon sea salt and serve.