01 - Set the oven to 400°F.
02 - Slice the top off the garlic bulb to expose cloves, drizzle with olive oil, wrap in foil, and roast for 30 to 35 minutes until soft and golden. Allow to cool slightly.
03 - Steam cauliflower florets over boiling water for 12 to 15 minutes until tender. Drain thoroughly and let rest to remove excess moisture.
04 - Squeeze roasted garlic cloves from skins into a food processor or bowl. Add steamed cauliflower, butter, sour cream, milk, salt, and pepper.
05 - Blend or mash the mixture until smooth and creamy.
06 - Taste and adjust seasoning if necessary. Stir in half the chives, transfer to a serving bowl, and sprinkle remaining chives on top.