Place the tomatoes, celery, onion and garlic onto a large baking tray. Drizzle with olive oil, season with salt and pepper, then roast for 35–40 minutes until softened and lightly caramelised.
Transfer the roasted vegetables to a large saucepan. Stir through the tomato paste, pour in the vegetable stock and simmer for 10–15 minutes.
Remove from the heat, add the basil and blend until smooth using a stick blender or food processor. Stir through the cream if using and season to taste.
Combine the butter, garlic and parsley. Spread over the bread and toast under a hot grill or in the oven until golden and crisp.
Ladle the soup into bowls. Garnish with extra basil, cracked black pepper and a drizzle of cream if desired. Serve immediately with the warm garlic toast.
Notes
Roasting the vegetables brings out their natural sweetness and creates a rich, full-flavoured soup.For an extra indulgent finish, sprinkle with freshly grated parmesan before serving.This soup freezes well, making it perfect for preparing ahead and enjoying on busy weeknights.