Preheat oven to 200C. Add tomatoes, 3 garlic cloves, onions, olive oil, salt and pepper to a greased baking pan. Roast for 30 minutes, or until tender, stirring once or twice during the process. Remove from oven and let cool slightly.

Transfer roasted tomato mix to a medium sized pot with boiling chicken stock. Pour mixture into a soup pot and cook over medium-high heat until heated through and blend with stick blender.

Add olive oil to a hot pan, and fry 1 garlic clove, spring onion and prawns. Add pesto ingredients to a food processor and blend until medium consistency.Serve soup with a few prawns and a dollop of pesto.