In a blender, process the dried porcini mushrooms into a fine powder. Transfer 3 Tbs. of the porcini powder to a bowl (reserve the rest for another use). Add the bread crumbs, cheese and chopped parsley to the bowl, and season with salt and pepper.
Season the racks of lamb with salt and pepper. Let stand at room temperature for 1 hour.
Preheat an oven to 375ºF.
Drizzle each rack of lamb with 1 Tbs. of the olive oil, rubbing it evenly over the meat. Coat the lamb with the bread crumb mixture, pressing so it adheres.
Heat an 11-inch nonstick grill pan over medium-high heat. When the pan is just smoking, lightly spray with nonstick cooking spray. Add the racks of lamb and sear, turning once, until well browned, 1 to 2 minutes per side. Transfer the pan to the oven and roast until an instant-read thermometer inserted into the thickest part of the racks, away from the bone, registers 130ºF for medium-rare, 20 to 25 minutes, or until done to your liking. Transfer the racks to a carving board, cover loosely with aluminum foil and let rest for 15 minutes.
â€¨Meanwhile, in a blender, combine the 3/4 cup olive oil, the garlic, vinegar, the 1 teaspoons salt and pepper, to taste. Blend on high until well combined, about 1 minute. Add the parsley, mint and rosemary leaves and pulse, scraping down the sides of the blender occasionally, until the herbs are chopped. Pulse less for a chunkier consistency and more for a smoother consistency.
Carve the racks into individual chops and arrange on a warmed platter. Pass the sauce alongside.