01 - Set oven temperature to 400°F.
02 - Slice top quarter off garlic head to reveal cloves; drizzle with olive oil, wrap in foil and roast 35-40 minutes until soft and golden. Cool slightly, then squeeze out cloves.
03 - Place potatoes in large pot, cover with cold salted water, bring to boil and simmer 15-20 minutes until tender. Drain thoroughly.
04 - Return potatoes to pot; add roasted garlic, butter, warm milk, and cream. Mash until creamy and smooth.
05 - Add salt and pepper to taste; thin with additional milk if needed.
06 - Transfer to serving bowl and garnish with chives or parsley if desired.