Peel outer skins from garlic bulbs, leaving cloves together. Cut off top quarter of each bulb. Place bulbs, cut side up, in center of a piece of heavy-duty aluminum foil. Drizzle 1 teaspoon oil over each bulb; fold foil over garlic, sealing tightly. Bake at 425° for 45 minutes or until soft. Remove from oven; cool. Remove and discard garlic clove skins. Scoop out pulp; mash and stir until smooth.
Combine roasted garlic and remaining ingredients in a small bowl; stir well. Cover and chill 2 hours.