01 - Preheat oven to 400°F. Slice off the top quarter of the garlic head to expose cloves. Drizzle with olive oil, wrap in foil, and roast for 35 to 40 minutes until soft and golden. Allow to cool slightly, then extract roasted garlic cloves.
02 - Place potatoes in a large pot and cover with cold salted water. Bring to a boil, then reduce heat and simmer for 15 to 20 minutes until fork-tender. Drain thoroughly.
03 - Return potatoes to pot. Add roasted garlic, butter, warm milk, and cream. Mash until smooth and creamy.
04 - Season with salt and freshly ground black pepper to taste. Adjust consistency with additional milk if necessary.
05 - Transfer mashed potatoes to serving bowl and garnish with chopped chives or parsley if desired. Serve hot.