01 - Preheat oven to 400°F. Slice the top off the garlic head to expose the cloves. Drizzle with olive oil, wrap in foil, and roast for 30 minutes until soft and golden.
02 - Place potatoes in a large pot and cover with cold water. Add 1 teaspoon salt. Bring to a boil, then reduce heat and simmer for 15 to 18 minutes or until fork-tender.
03 - Drain potatoes thoroughly and return them to the pot.
04 - Squeeze the roasted garlic cloves out of their skins and add to the potatoes.
05 - Add butter and warmed milk to the potatoes and garlic. Mash until smooth and creamy, adding more milk if necessary.
06 - Stir in remaining salt and black pepper. Taste and adjust seasoning as needed.
07 - Transfer to a serving bowl, top with additional butter and chopped herbs if desired. Serve hot.