01 - Preheat oven to 400°F. Arrange halved tomatoes cut side up and the sliced garlic head on a baking sheet. Drizzle with 1 tablespoon olive oil and season with salt and pepper.
02 - Roast for 30 minutes until tomatoes soften and garlic turns golden and fragrant. Remove and let cool slightly.
03 - Heat remaining 1 tablespoon olive oil in a large pot over medium heat. Add chopped onion, diced carrot, and celery; sauté for 5 to 7 minutes until softened.
04 - Squeeze roasted garlic cloves from skins into the pot. Add roasted tomatoes with juices, dried thyme, and red pepper flakes if desired.
05 - Pour in vegetable broth and bring mixture to a simmer. Cook for 10 to 15 minutes, stirring occasionally.
06 - Remove from heat. Blend the soup until smooth using an immersion blender or working in batches with a countertop blender, allowing to cool slightly if needed.
07 - Return soup to the pot and stir in heavy cream. Gently reheat without boiling. Adjust seasoning to taste.
08 - Serve hot, garnished with fresh basil and a drizzle of olive oil or extra cream if desired.