Preheat oven to 400℉
Spread cauliflower on a baking tray. Add salt, pepper, garlic powder, onion powder, turmeric, and paprika. Use 3 tablespoons of olive oil and mix everything together until evenly combined.
Slice the head off the garlic and place it on a piece of silver foil. Drizzle olive oil over the garlic, covering completely. Wrap it tightly and add it to the corner of the baking tray.
Roast until the cauliflower is golden brown- roughly 30 minutes.
Heat the remaining 3 tablespoons of olive oil in a pot over medium heat. Chop the onion and add it to the pot until it's translucent. Add roasted garlic pulp and let it sit for a couple of minutes. Add roasted cauliflower and any extra juices. Cook for another few minutes.
Add the milk and water/stock. Bring to a boil and let it simmer for 10 mintues.
Blend the soup until smooth and creamy.
Season with salt and pepper.