Parboil potatoes 5 minutes in salted water. Let cool then cut into wedges or chunks and dress with oil in a roasting pan. Toss with whole, cracked garlic cloves and chopped rosemary, salt and pepper.
Preheat oven to 425°F.
Using a cleaver, a large sharp kitchen knife or shears, split bird down the back, open and flatten it. Butterfly it then loosen the skin all over the bird, being careful not to tear it. Dress with EVOO, season with salt and pepper.