Preheat your oven to 425°F (220°C).
In a small bowl, combine olive oil, minced garlic, chopped rosemary, chopped thyme, Dijon mustard, salt, and black pepper to create a marinade.
Place the rack of lamb on a cutting board with the meaty side facing up. Using a sharp knife, score the fat in a crosshatch pattern without cutting into the meat.
Rub the marinade mixture all over the rack of lamb, ensuring it gets into the scored fat and on both sides of the meat.
Place the marinated rack of lamb in a roasting pan with the bone side facing down.
Roast in the preheated oven for about 25 minutes, or until the internal temperature reaches 135°F (57°C) for medium-rare.
Remove the lamb from the oven and let it rest for 10 minutes before slicing to allow the juices to redistribute.
Slice between the bones into individual chops and serve.