Place halved tomatoes cut side up on a baking sheet lined with parchment paper. Slice garlic cloves in half, and place on top of tomatoes. Liberally drizzle 2-3 tablespoons of olive oil over top. Sprinkle with approximately ½ tablespoon of salt. Set aside.
On another baking sheet, lined with parchment, arrange onion, celery and peppers. Drizzle with remaining oil and sprinkle with remaining salt.
Place in the preheated oven and roast for 45-60 minutes.
Add roasted vegetables to a large soup pot, make sure to include juices. Add tomato paste, stock and thyme. Bring to a simmer. Remove from heat and blend until smooth using immersion blender or Vitamix. Return to pot and add cream. Stir to combine.
Serve topped with parmesan petals or crumbled goat cheese.