Pour the extra virgin olive oil into a cast iron skillet, or other heavy skillet and let warm up, add in your potatoes and lightly brown on all sides. Seasoning with salt and pepper. Toss in herbs if using. Put a tight fitting lid on and let steam fry on low-medium heat until nearly done.
Pull potatoes off the fire and let cool enough to handle. Wrap each potato in a torn piece of Prosciutto. Place in a little gratin dish and dot with butter. Roast at 400 until a bit blistered, turning once to brown both sides.