Place cauliflower florets and garlic cloves on a rimmed baking sheet. Drizzle with about 1 ½ tablespoons of olive oil and lightly sprinkle with ½ teaspoon of salt and cracked pepper to taste. Toss to coat evenly using your hands. Roast for 15-20 minutes until tender and lightly browned, tossing occasionally. Optional: reserve a few roasted pieces for soup topping)
In a large pot, heat the remaining olive oil over medium heat. Add onions and celery and sauté until tender and lightly browned, about 5-6 minutes.
Stir in thyme and cumin, and sauté for 30-60 seconds until fragrant.
Add the roasted cauliflower, garlic cloves, broth, bay leaf, salt, and pepper. Bring the mixture to a boil, then reduce heat to a gentle simmer. Cook for 8-10 minutes, then remove from heat and discard the bay leaf.
Stir in the coconut milk. Using an immersion blender or regular blender, blend until the soup is very creamy and smooth. If the consistency is too thick, you can add a little vegetable broth to thin it out. Taste for seasoning and adjust as needed.
Serve in bowls topped with some baked cauliflower florets and more fresh thyme leaves.
Notes
Cut cauliflower into uniform sizes for even roasting and to avoid uneven cooking.
Deglaze the baking sheet with broth or water after roasting to capture flavorful browned bits.
Soups thicken as they cool, so adjust broth accordingly.