01 - Set the oven to 400°F.
02 - Slice the garlic bulb's top to expose cloves, drizzle with olive oil, wrap in foil, and roast for 30 minutes until soft and golden.
03 - Boil a large pot of water, add cauliflower florets, and cook for 10 to 12 minutes until tender. Drain thoroughly.
04 - Combine cooked cauliflower, roasted garlic cloves squeezed from their skins, butter, sour cream, milk, salt, and pepper in 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 if necessary, transfer to a serving dish, sprinkle with remaining chives, and serve warm.