Preheat the oven to 350°F.
Cut off the tips of the heads of garlic and brush the cut sides with 1 tablespoon of the olive oil. Set garlic cut-side down on a sheet pan and roast until it is soft to the touch, about 30 minutes. Let garlic cool for 5 minutes, then squeeze the roasted cloves out of the garlic and into a bowl. Mash with a fork and spread over the top of the lamb (see tip).
Meanwhile, place the lamb in a large roasting pan and season with salt, pepper and half of the rosemary. Allow to stand at room temperature for 30 minutes to an hour. Place the potatoes in an oven-proof dish and toss with the remaining oil and rosemary. Set aside.
Roast lamb for about 1 hour 40 minutes, until it registers 130-135°F on a meat thermometer for a medium-rare roast, or until the juices run clear when a sharp knife or skewer is inserted in the thickest part of the meat.
When the lamb has been roasting for 40 or 50 minutes, place the potatoes in the oven and bake until well browned and tender.
Transfer the lamb to a warm platter and let rest for 15 minutes. (It will continue to cook as it rests.) Carve and serve with the potatoes and asparagus.
TIP: The garlic can be roasted and mashed the day before. Store in a tightly sealed container in the refrigerator. You could also spread over the lamb the day before and marinate overnight for a real garlic flavor. Just remember to cover well, and bring lamb to room temperature before roasting.
Serves 6-8. Submitted by: Karen
