- 1. Preheat the oven to 375°F. 
- 2. Rub the racks of lamb with the olive oil, garlic, rosemary, and salt and pepper. 
- 3. Place the racks of lamb in a roasting pan and bake in the preheated oven for 25-30 minutes, or until the lamb is cooked through. 
- 4. Remove the lamb from the oven and allow to rest for 10 minutes before carving. 
- 5. Meanwhile, in a small saucepan, melt the butter and add the beef or veal stock. Simmer for 10 minutes, or until the sauce has reduced by half. 
- 6. Carve the lamb into individual chops and serve with the rosemary jus.