Add olive oil to a large soup pot over medium high heat. Once hot, add carrots, onions, and celery and sauté for a few minutes.

Add diced tomatoes, tomato paste, chicken broth, oregano, and dried basil. Bring to a gentle boil and cook until the vegetables are tender.

Use an immersion blender or regular blender to puree the soup until smooth, if desired. Return to the soup pot.

In a separate pot, melt butter over medium low heat. Stir in flour and whisk constantly for about 10 minutes until the roux is a nice golden brown color.

Add a big ladle of the soup to the roux to form a thick paste. Add a few more scoops of soup and stir well until smooth.

Add the roux mixture to the soup pot and stir to combine.

Stir in parmesan cheese, half and half, salt, pepper, and basil. Adjust seasonings as needed.

Cook for a few more minutes until warmed through. Store covered in the refrigerator for up to one week.