01 - Preheat oven to 400°F. Slice the top off the garlic head to expose cloves. Drizzle with olive oil, wrap in aluminum foil, and roast for 35-40 minutes until soft and golden. Remove and cool.
02 - Place potatoes in a large pot and cover with cold water. Add a generous pinch of salt. Bring to boil, reduce to simmer, and cook until fork-tender, approximately 15-20 minutes.
03 - Drain potatoes thoroughly and return to the hot pot. Steam off excess moisture for 2 minutes.
04 - Squeeze roasted garlic cloves from their skins into the potatoes. Add butter, warm milk, and cream to the pot.
05 - Mash until smooth and creamy using a potato masher or ricer. Season generously with salt and pepper. Taste and adjust seasoning as needed.
06 - Transfer to serving bowl and garnish with chopped chives or parsley if desired. Serve immediately while hot.