Preheat oven to 350°F. With sharp knife, cut tops off of garlic bulbs. Place on large, square of foil and brush with olive oil. Wrap in foil. Bake until very soft (about 45 minutes). Let cool for easier handling, then squeeze garlic from head into small bowl.
Rinse cauliflower and remove core with knife. Break remaining cauliflower into florets.
Bake – boil – steam or microwave cauliflower florets until very tender. (Quickest method: Microwave on high for about 6-8 minutes until tender).
Turn cooked florets into food processor or blender. Add roasted garlic, butter or sour cream and blend until smooth. OR: press ingredients through ricer or mash with potato masher until smooth.