Preheat the oven to Roast at 350°F with the rack near the center of the oven.
Rinse and pat the lamb racks dry. Trim any excess fat from the racks. Season lightly with salt and pepper.
Heat a large skillet (cast iron is preferred) over high heat. One rack at a time, sear the meat on the racks until nicely browned, about 2 minutes per side. If desired, this can be done an hour or two ahead of time; just leave the lamb at room temperature after searing.
In a bowl, whisk together the Dijon mustard, olive oil, honey, Worcestershire sauce, paprika, herbs, and garlic. Season lightly with salt and pepper. In another bowl combine the breadcrumbs and Parmigiano-Reggiano cheese.
Brush the meat of the lamb racks with the mustard mixture. Roll the racks in the bread crumb/Parmigiano-Reggiano mixture, pressing the crumbs to help them adhere.
Place the racks, bone side down (you may need to interlock the bone ends to make them fit) on a baking sheet pan or in a roasting pan. Arrange the racks so the meaty part faces outside of the pan. Roast for 20-30 minutes, depending on size and preferred doneness. (You can use an instant-read thermometer inserted into the center of the meat to check the doneness; 125-130°F for rare - 135-140°F for medium).
Remove from oven and allow to rest for about 5 minutes. Carve and serve.
6 servings