Leg of Lamb with Pistachio Couscous Recipe

1 (6 to 8 lbs.) leg of lamb, aitchbone removed by butcher, trimmed; 5 tablespoons extra – virgin olive oil ; 9 garlic cloves (7 cloves sliced and 2 finely chopped); 1/4 cup honey; 1/4 cup fresh lemon juice; 1 tablespoon finely chopped fresh rosemary …