Roast the garlic: Slice the tops off the garlic bulbs. Drizzle with oil. Wrap in foil. Bake at 400°F for 40 minutes.
Prep potatoes: Peel and cut into 2-inch pieces. Place in pot with bay leaves and salt. Cover with cold water.
Cook until tender: Bring water to a boil. Reduce heat and simmer for 15 minutes. Check with a fork for doneness.
Drain well: Pour potatoes into colander. Return to pot. Let dry over low heat for 1 minute.
Mash everything: Push potatoes through a ricer or use a masher. Squeeze in roasted garlic cloves. Mix gently until combined.
Add warm dairy: Heat butter and milk together. Pour into the potatoes while stirring. Mix just until smooth. Add salt and pepper as needed.
Serve and enjoy: Transfer with a spoon to a bowl. Serve hot with extra butter or chopped parsley on top if desired.