Preheat an outdoor grill for medium-high heat and lightly oil the grate.
Place garlic bulbs on large sheets of aluminum foil, up to 3 bulbs per sheet. Lightly drizzle olive oil over bulbs and season with salt and pepper. Wrap foil tightly around bulbs.
Place bulbs inside the preheated grill on the top rack away from the flames; cook until garlic cloves are butter-soft, about 30 minutes. Allow garlic bulbs to cool until easily handled. Squeeze garlic from bulb into a bowl and mash with a fork until spreadable.
