01 - Set the oven to 400°F and prepare for roasting.
02 - Slice the top off the garlic bulb to expose cloves, drizzle with olive oil, wrap in foil, and roast for 30 minutes until soft and golden.
03 - Bring a large pot of water to a boil, add cauliflower florets, and cook for 10 to 12 minutes until tender. Drain thoroughly.
04 - Place cooked cauliflower, roasted garlic cloves (squeezed from skins), butter, sour cream, milk, salt, and pepper into a bowl or food processor; mash or blend until smooth and creamy.
05 - Fold in most of the chopped chives, reserving a few for garnish.
06 - Adjust seasoning to taste, transfer to serving dish, sprinkle with remaining chives, and serve warm.