01 - Preheat oven to 400°F (204°C) and line a baking sheet with parchment paper.
02 - Arrange halved tomatoes cut side up on baking sheet. Drizzle with 1 tablespoon olive oil, season with salt and pepper. Cut top off garlic head, drizzle with 1 tablespoon olive oil, wrap tightly in foil, and place on sheet.
03 - Roast tomatoes and garlic for 30 to 35 minutes until tomatoes are caramelized and garlic is tender. Allow to cool slightly.
04 - In a large pot, heat remaining 1 tablespoon olive oil over medium heat. Add chopped onion and sauté for 5 minutes until soft and translucent.
05 - Squeeze roasted garlic from skins into pot. Add roasted tomatoes, broth, and basil. Blend with immersion blender until perfectly smooth, or blend in batches in a stand blender.
06 - Return soup to pot if needed, stir in cream or coconut milk, and simmer 5 to 10 minutes to meld flavors. Adjust salt, pepper, and red pepper flakes as desired.
07 - Ladle into bowls and garnish with fresh basil, a swirl of cream, or roasted cherry tomatoes if desired. Serve hot.