Directions

1. Let lamb stand at room temperature for one hour. Heat oven to 325 degrees. Remove all but a thin layer of fat from the lamb. Rub lamb with 1 tablespoon oil; sprinkle with 1 teaspoon salt and 1/4 teaspoon pepper. Place on a rack in a heavy roasting pan.
2. Meanwhile, rub head of garlic with 1/4 teaspoon oil; wrap loosely in foil. Bake until garlic is very soft, about 1 hour. Let cool.
3. Cut off top of garlic head; squeeze roasted garlic into a bowl. Using a fork, mash garlic to a paste. Add extra-virgin olive oil, lemon juice, oregano, parsley, and remaining 1/4 teaspoon salt and 1/4 teaspoon pepper; mix well.
4. Rotate pan after lamb has roasted 1 1/4 hours. After 30 minutes more, slather lamb with roasted-garlic paste. Roast an additional hour (for a total roasting time of about 2 3/4 hours), or until an instant-read thermometer inserted at the thickest part reads 160 degrees. Remove from oven, and let rest 20 minutes.
5. Transfer lamb to a carving board. Pour off fat from roasting pan; place over medium-high heat. Sprinkle with flour, and stir with a wooden spoon. Pour in brandy; scrape up brown bits from bottom of pan. Lower heat to medium; let liquid reduce by half. Add stock, stirring until incorporated. Add rosemary and salt and pepper to taste.
6. Slice lamb; serve with sauce on the side.