Step 1: Roast the Tomatoes : Preheat your oven to 400°F (200°C). Place the halved tomatoes, chopped onion, and garlic cloves on a baking sheet. Drizzle with olive oil, sprinkle with salt, pepper, and thyme, and toss well to coat. Roast in the oven for 25–30 minutes, until the tomatoes are soft and slightly caramelized at the edges.
Step 2: Blend the Soup : Transfer the roasted vegetables (and all their juices) into a blender or food processor. Add the tomato paste and about half of the broth. Blend until smooth and creamy. Pour the mixture into a pot and add the remaining broth. Bring to a gentle simmer over medium heat.
Step 3: Season and Finish : Taste the soup — add a pinch of sugar if the tomatoes are too acidic. Stir in heavy cream or milk if you prefer a richer texture. Simmer for 5–10 minutes to meld the flavors. Adjust salt and pepper as needed.
Step 4: Make the Cheesy Toast : While the soup simmers, preheat your oven broiler (or a toaster oven). Place bread slices on a baking tray and brush lightly with butter or olive oil. Top each slice with shredded cheese and sprinkle oregano or chili flakes if desired. Broil for 2–3 minutes, until the cheese melts and turns golden.
Step 5: Serve and Enjoy : Ladle the hot soup into bowls. Top with fresh basil or parsley. Serve immediately with the warm, cheesy toast on the side (or dipped right in!).