01 - Preheat 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 30-35 minutes until soft and golden.
03 - Steam cauliflower florets over boiling water for 12-15 minutes until very tender, then drain and let sit to release excess moisture.
04 - Squeeze roasted garlic cloves from their skins into a food processor or large bowl.
05 - Add steamed cauliflower, butter, sour cream, milk, salt, and pepper; blend or mash until smooth and creamy.
06 - Taste mixture and adjust salt and pepper as desired.
07 - Stir in half of the chopped chives.
08 - Transfer to a serving bowl and garnish with the remaining chives.