Preheat the oven to 400ºF.
Cut each head of the garlic crosswise in half. Toss the garlic heads with the olive oil, salt, and pepper in a bowl. Turn out the garlic heads onto the center of a sheet of aluminum foil. Bring the ends of the foil together to make a small bag or pouch. Roast for 1 hour, or until the garlic is tender.
Remove the bag from the oven and open it up a bit. Return to the oven for about 10 minutes more. Remove the flesh by squeezing each half clove with your thumb and index finger.
Use immediately or refrigerate in a little olive oil in an airtight container for 2 to 3 days.
Yield: about 1 cup