Heat the oven to broil and arrange a rack about 5 to 6 inches below the heating element.
Set a large plate aside. Place the asparagus in a 12″ cast iron skillet, drizzle it with the olive oil, and season with salt and pepper. Using your hands, toss until the spears are evenly coated with the oil. Transfer them to the large plate and set the skillet aside. Starting just under the scaled tip of the asparagus, wrap each spear with 1 slice of prosciutto in a downward spiral toward the cut end, just barely overlapping the seams of the prosciutto. Place back onto the skillet.
Repeat with the remaining asparagus, leaving as much space as possible between each spear.
Broil for 3 minutes, remove the skillet from the oven and flip the asparagus over. Return to the oven and continue to broil until the asparagus is charred in spots and the prosciutto is crisped and browned, about 3 minutes more.