Place the halved tomatoes on a baking sheet, drizzle with olive oil, and sprinkle with salt and pepper. Roast in the oven for 30-40 minutes until the tomatoes are caramelized.
In a large pot, heat the remaining olive oil over medium heat. Add the chopped onion and garlic, sauté until translucent.
Add the roasted tomatoes, dried basil, dried oregano, and vegetable broth to the pot. Bring to a simmer and cook for 15-20 minutes.
Use an immersion blender to blend the soup until smooth. Alternatively, transfer the soup in batches to a blender and blend until smooth. Be careful as the soup will be hot.
Stir in the heavy cream and season with salt and pepper to taste.
Simmer the soup for an additional 5 minutes to allow the flavors to meld together.
Serve the creamy roasted tomato soup hot, garnished with fresh basil leaves.