01 - Preheat oven to 375°F. Toss bread cubes with olive oil, garlic powder, and salt. Spread evenly on a baking sheet and bake for 12 to 15 minutes, turning halfway, until golden and crisp.
02 - In a large pot, heat 2 tablespoons olive oil over medium heat. Add diced onion, carrot, and celery; sauté for 6 to 8 minutes until tender.
03 - Stir in minced garlic and cook for 1 minute until aromatic.
04 - Add tomatoes with their juices, fresh basil leaves, vegetable broth, sugar, salt, black pepper, and optional red pepper flakes. Bring mixture to a gentle simmer.
05 - Reduce heat and simmer uncovered for 20 to 25 minutes, stirring occasionally, until vegetables are very soft.
06 - Remove pot from heat. Using an immersion blender or working in batches with a blender, puree soup until completely smooth.
07 - Stir in heavy cream gently. Reheat if necessary and adjust seasoning to taste.
08 - Ladle the bisque into bowls. Garnish with crispy croutons and additional fresh basil leaves.