Preheat the oven to 325 degrees F. Line a small baking dish with aluminum foil.
Cut the top quarter from each head of garlic and place, cut side up, on the prepared dish. Drizzle with oil and season lightly with salt and pepper. Turn the garlic cut side 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 the cloves into an airtight container and refrigerate until ready to be used.
Yield: Each head yields about 1 1/2 tablespoons, 2 heads about 3 tablespoons