How to Make It
Preheat the oven to 350°. Season the lamb racks with salt and pepper. In a large ovenproof skillet, heat 1 tablespoon of the olive oil until shimmering. Add 1 of the lamb racks and cook over moderately high heat until browned all over, about 10 minutes. Transfer the lamb to a platter and brown the other rack. Return both of the lamb racks to the skillet with the ribs pointing up. Rub each rack with 3 of the garlic cloves and 1/2 tablespoon of the butter and tuck the thyme sprigs underneath. Roast the lamb 10 minutes for medium rare, or until an instant-read thermometer inserted in the center of the meat registers 130°. Transfer the lamb to a cutting board, cover loosely and let stand for 10 minutes before slicing.
Meanwhile, pour off the fat in the skillet and discard the thyme, then set the skillet over high heat. Add the veal stock and simmer, scraping up any browned bits on the bottom. Mash the remaining 2 garlic cloves and add them to the skillet with the chopped tomatoes; cook until slightly thickened, about 5 minutes. Reduce the heat to low and whisk in the remaining 3 tablespoons of olive oil and 1 tablespoon of butter. Season with salt and pepper and keep warm.
Cut the lamb into double chops between the ribs and serve with the tomato jus and roasted tomatoes.