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, cover with cold water, add 1 teaspoon salt. Bring to a boil, then simmer for 15–18 minutes until fork-tender.
03 - Drain potatoes thoroughly and return them to the pot.
04 - Squeeze roasted garlic cloves from skins into the potatoes. Add butter and warmed milk, then mash until smooth and creamy, adding more milk if needed.
05 - Season with remaining salt and black pepper. Adjust to taste. Transfer to a serving dish, top with additional butter and chopped herbs if desired. Serve warm.