01 - Heat olive oil in a large pot over medium heat. Add onion and sauté until translucent, about 5 minutes.
02 - Add garlic and cook for 1 minute until fragrant.
03 - Stir in tomatoes with juices, vegetable broth, sugar, salt, and pepper. Bring to a boil, reduce heat, and simmer uncovered for 20 minutes.
04 - Remove from heat. Add basil leaves. Using an immersion blender, purée the soup until smooth, or carefully transfer to a blender in batches.
05 - Stir in the heavy cream and gently reheat over low heat without boiling. Adjust seasoning as needed. Ladle into bowls and garnish with extra basil leaves.