Rub off any loose papery skin from the garlic, and trim about a 1/2 inch off the top of each head, to expose the cloves. Set the garlic snugly in an ovenproof baking dish just large enough to hold them. Drizzle with the oil and season with the salt and pepper. Cover with foil and cook for about 40 minutes. Remove foil and bake until the heads are soft and the tops golden brown, another 30 minutes. Allow garlic to cool.
Serve the garlic whole for a rustic garnish, or break the heads apart and squeeze the garlic out of skins to eat the whole clove. To store the garlic, place it in a container and cover with olive oil. Store in the refrigerator for up to a week. Use skinned roasted garlic to season mashed potatoes, in salad dressings, to flavor and thicken sauces, or on sauteed or roasted vegetables.