Step 1: Preheat the Oven

1. Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper for easy cleanup.

Step 2: Prepare the Tomatoes

1. Spread the halved or quartered tomatoes, onion wedges, and garlic cloves evenly on the baking sheet.
2. Drizzle with olive oil and sprinkle with salt and black pepper. Toss gently to coat.

Step 3: Roast the Vegetables

1. Roast the vegetables in the preheated oven for 35–40 minutes, or until the tomatoes are soft and slightly caramelized, and the onions are golden around the edges.

Step 4: Blend the Soup

1. Transfer the roasted vegetables to a large pot or blender. Add the fresh basil leaves and 2 cups of broth.
2. Use an immersion blender or a high-speed blender to puree the mixture until smooth. Add more broth to reach your desired consistency.

Step 5: Simmer the Soup

1. Place the pot over medium heat. Stir in the sugar (if using) and red pepper flakes for a touch of heat. Simmer for 10 minutes to allow the flavors to meld.

Step 6: Add Cream (Optional)

1. For a creamier soup, stir in the heavy cream or coconut milk during the last few minutes of simmering. Adjust seasoning with additional salt and pepper, if needed.

Step 7: Serve

1. Ladle the soup into bowls and garnish with fresh basil leaves, a drizzle of olive oil or cream, and croutons or shredded Parmesan cheese. Serve warm with your favorite bread or sandwich.