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