01 - Preheat oven to 375°F. Toss bread cubes with olive oil, garlic powder, and salt. Spread on a baking sheet and bake for 10–12 minutes, turning once, until golden and crisp. Set aside.
02 - In a large pot, heat 1 tablespoon olive oil over medium heat. Add onion, carrot, and celery. Sauté for 5–7 minutes until softened.
03 - Add garlic and cook for 1 minute until fragrant. Stir in tomato paste and cook for 1 minute.
04 - Add tomatoes with juices, vegetable broth, sugar, salt, pepper, and red pepper flakes if using. Bring to a boil, then reduce heat and simmer uncovered for 20 minutes.
05 - Stir in basil leaves and remove from heat. Using an immersion blender or working in batches with a blender, puree the soup until completely smooth.
06 - Return soup to low heat. Stir in heavy cream and gently warm through, being careful not to boil. Adjust seasoning to taste.
07 - Ladle soup into bowls, top with croutons and extra fresh basil to serve.