Heat olive oil in a pan over medium-high heat. Sear the lamb racks on all sides until browned.
Mix garlic, rosemary, and thyme in a bowl. Rub this mixture over the lamb.
Place the lamb racks in a roasting pan and roast in the preheated oven for 20-25 minutes, or until the internal temperature reaches 135°F (57°C) for medium-rare.
Let the lamb rest for 10 minutes before slicing and serving.