2Place garlic in a casserole dish and drizzle with olive oil.
3Roast garlic in the preheated oven until tender and fragrant, about 15 minutes.
4Place a steamer insert into a saucepan and fill with water to just below the bottom of the steamer. Bring water to a boil. Add cauliflower, cover, and steam until tender, about 10 minutes.
5Mash cauliflower and roasted garlic with olive oil together in a bowl. Stir salt, parsley, and pepper into mashed cauliflower until completely incorporated. Spread cauliflower mixture into casserole dish.
6Bake mashed cauliflower in the preheated oven until hot and flavors blend, about 15 minutes.