Preheat the oven to 350 degrees F.
Line a baking sheet with parchment or aluminum foil.
Cut the top quarter from the heads of garlic and place, cut side up, on the prepared baking sheet. Drizzle each with oil and sprinkle lightly with salt and pepper.
Turn the garlic cut sides down, and roast until the cloves are soft and golden brown, about 1 hour. Remove from the oven and let sit until cool enough to handle. Squeeze each head of garlic, gently pressing with your fingers to expel the cloves into a bowl. Mash with a fork and blend thoroughly.