1 stick unsalted butter, softened to room temperature
1 cup bread crumbs,1/2 cup grated Parmigiano-Reggiano
1/4 cup finely chopped onion
2 teaspoons chopped rosemary
Salt and freshly ground black pepper
3 8-rib racks of lamb, trimmed
4 tablespoons olive oil
5 cloves garlic, crushed
3 sprigs thyme
Preheat oven to 450 degrees F or 230 degrees C.
In a small bowl, stir together butter, bread crumbs, Parmigiano-Reggiano, onion, and rosemary, until they come together to form a ball. Season with salt and pepper, and set aside.
Brush the racks of lamb with oil, and season with salt and pepper. Set a sauté pan over medium heat, and add 2 tablespoons olive oil, garlic, and thyme. Sear the lamb, one rack at a time, for 1 minute per side or until golden brown, and transfer to a baking sheet. Roast the racks for 10 minutes, reduce the oven temperature to 350 degrees F or 180 degrees C, and continue cooking until the lamb’s internal temperature reaches 130 degrees F or 55 degrees C (medium-rare; start checking after 5 minutes at 350 degrees F or 180 degrees C).
Transfer the racks of lamb to a work surface, and allow to rest for 5 minutes before coating the meat with the breadcrumb mixture. Broil the racks for a few minutes, watching carefully, until the crust turns golden brown.