Preheat oven to 350 degrees.
Cut slits in the top of the leg of lamb every 3 to 4 inches, deep enough to push slices of garlic down into the meat. 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.