01 - Preheat oven to 400°F.
02 - Slice the top off the garlic bulb, drizzle with 1 tablespoon olive oil, wrap in foil, and place on a baking sheet.
03 - Place cauliflower florets on the baking sheet with the garlic. Drizzle remaining olive oil over cauliflower and toss to coat evenly.
04 - Roast cauliflower and garlic for 30 minutes, stirring cauliflower halfway through, until golden and tender.
05 - In a large pot, melt butter over medium heat. Add onion, carrots, and celery. Sauté for 5 to 6 minutes until softened.
06 - Squeeze roasted garlic cloves from skins and add to the pot along with the roasted cauliflower.
07 - Pour in vegetable broth and bring to a simmer. Cook for 10 minutes to allow flavors to meld.
08 - Remove from heat. Use an immersion blender to puree soup until smooth, or carefully transfer to a blender in batches.
09 - Stir in Asiago cheese and milk. Return to low heat, stirring constantly until cheese melts completely and soup reaches creamy consistency.
10 - Season with salt, pepper, smoked paprika, and nutmeg. Serve hot, garnished with parsley or chives and extra Asiago cheese if desired.