Cut the top off garlic bulbs so each clove is exposed. Brush with oil; wrap in foil. Bake at 350° for 45 minutes or until garlic is very soft. Cool for 5 minutes. Remove garlic from skins; mash and set aside.
Place potatoes in a saucepan and cover with water. Bring to a boil; cover and cook for 20-25 minutes or until very tender. Drain well. Add milk, butter, rosemary, salt and garlic; mash until light and fluffy. Yield: 6 servings.