01 - Set oven to 375°F and prepare for baking croutons.
02 - Heat olive oil in a large pot over medium heat. Add diced onion, carrot, and celery. Cook for 6 to 8 minutes until softened.
03 - Incorporate minced garlic and cook for 1 minute until fragrant.
04 - Stir in canned tomatoes with juices, fresh basil leaves, vegetable broth, sugar, salt, black pepper, and optional red pepper flakes. Bring to a simmer.
05 - Reduce heat and simmer uncovered for 20 to 25 minutes, stirring occasionally, until vegetables are very tender.
06 - Toss bread cubes with olive oil, garlic powder, and salt. Spread evenly on a baking sheet and bake for 12 to 15 minutes, tossing halfway through, until golden and crisp.
07 - Remove pot from heat. Use an immersion blender or process in batches in a blender until the soup is completely smooth.
08 - Stir in heavy cream and gently rewarm if necessary. Adjust seasoning to taste.
09 - Ladle soup into bowls and garnish with homemade croutons and extra basil leaves.