Instructions:

1. Heat olive oil and butter in a large pot over medium heat until melted. Add diced onion and sauté until translucent, about 5 minutes.

2. Add chopped carrots and cook for another 5 minutes, stirring occasionally to caramelize slightly.

3. Stir in minced garlic, chili flakes, and Italian seasoning. Cook for 1 minute until fragrant.

4. Pour in balsamic vinegar, then add the canned whole plum tomatoes. Crush tomatoes gently with a spoon.

5. Add vegetable broth, bring to a simmer, and cook uncovered for about 20 minutes, until carrots are tender.

6. Use an immersion blender or transfer in batches to a blender and puree until smooth.

7. Stir in heavy cream and season with salt and freshly ground black pepper.

8. Tear fresh basil leaves and stir into the soup before serving. Drizzle with extra cream if desired.