Preheat the oven to 400°F. Line a baking sheet with foil.
Use a knife to cross-hatch the fat on the lamb rack and place on the baking sheet fat-side-up. Season the lamb with salt and pepper. Cover the bones with foil. Roast, uncovered, for 25 minutes. If you have a meat thermometer, use it. Medium rare will be about 145°F. If you're shooting for medium rare, pull it out of the oven at about 125℉.
In a small bowl, mix together the oil, breadcrumbs, and seasonings. Work the mixture into a paste and spread on top of the lamb (make more paste if needed).
Roast the lamb 15 minutes more, depending on the degree of desired doneness. Again, if you're looking for medium rare, pull it out at 145°F. Cover with foil and let rest for 10 to 15 minutes before slicing.