1. Preheat the oven to 375°F.
2. Arrange the tomato halves on a baking sheet. Drizzle with olive oil, then sprinkle with salt and black pepper.
3. Roast the tomatoes for 1 hour. Remove from the oven and set aside.
4. In a large pot or Dutch oven, heat 2 tablespoons of olive oil or butter over medium-high heat.
5. Add the diced onion and sauté for about 5 minutes until softened.
6. Stir in the garlic, thyme, salt, and pepper, and sauté for another minute.
7. Add the crushed tomatoes, basil, and sugar to the pot. Reduce the heat and simmer for about 10 minutes.
8. Pour in the chicken stock and add the roasted tomatoes. Simmer for 30 minutes, stirring occasionally.
9. Use an immersion blender to puree the soup, or carefully transfer it in batches to a blender or food processor. Return the pureed soup to the pot.
10. Stir in the heavy cream.
11. To prepare mini croutons, cut a few small pieces of bread into cubes. Toss with a little oil, diced garlic, and basil, then bake at 400°F for about 7 minutes until crisp.
12. Serve the soup immediately topped with the homemade croutons.