Preparation Cut excess fat from leg of lamb, leaving thin layer. Set lamb in medium roasting pan. Make several slits in lamb and spoon some pesto into each. Rub remaining pesto into lamb. Cover lamb and let stand 2 hours at room temperature or refrigerate overnight. Preheat oven to 350°F. Roast lamb 30 minutes. Add shallots to pan, turning to coat in pan juices. Roast 45 minutes. Add radicchio, turning, to coat in juices. Continue roasting until thermometer inserted into thickest part of meat registers 140°F for medium-rare, about 45 minutes longer. Remove from oven and let stand 15 minutes. Transfer lamb, shallots and radicchio to platter. Garnish with fresh basil sprigs and serve.
Preparation Cut excess fat from leg of lamb, leaving thin layer. Set lamb in medium roasting pan. Make several slits in lamb and spoon some pesto into each. Rub remaining pesto into lamb. Cover lamb and let stand 2 hours at room temperature or refrigerate overnight. Preheat oven to 350°F. Roast lamb 30 minutes. Add shallots to pan, turning to coat in pan juices. Roast 45 minutes. Add radicchio, turning, to coat in juices. Continue roasting until thermometer inserted into thickest part of meat registers 140°F for medium-rare, about 45 minutes longer. Remove from oven and let stand 15 minutes. Transfer lamb, shallots and radicchio to platter. Garnish with fresh basil sprigs and serve.