1. While the garlic bakes, heat one tablespoon oil in a pot over medium-low heat.
2. Add leeks and onions and sweat for 10 to 15 minutes (not less – this is where you build flavor).
3. Add cauliflower and potatoes. Cover with chicken broth and bring to a boil, then reduce to a simmer.
4. Remove garlic from the oven and add to the pot, along with the oil. Simmer for one hour.
5. With an immersion blender or in a food processor, blend soup until smooth and creamy. Season with salt and pepper to taste.