Directions. 1  Preheat oven to 450 degrees. 2  Season lamb racks with salt and pepper; coat each evenly with 3 Tbsp pesto. 3  Roast on baking sheet until about 5 degrees less than desired doneness (about 20 min for medium). 4  Transfer lamb to clean platter; let rest 10 min before slicing.
Preheat the oven to 400 degrees F. Using your hands, rub the lamb all over with the lemon juice. Pat the garlic and rosemary evenly all over the surface of the meat. Season the meat with the salt and pepper and place the lamb in a roasting pan. Place the lamb in the oven and roast for 30 minutes.
Salt and pepper generously all over the top of lamb, place several sprigs of fresh rosemary under and on top of the lamb. Place lamb on roasting pan. Roast in preheated oven until the lamb is cooked to your desired doneness, about 1 3/4 to 2 hours. Do not overcook the lamb, the flavor is best if meat is still slightly pink. Let rest at least 10 minutes before carving.