In a large pot, saute carrots and onions over medium heat in the olive oil until soft about 6-7 minutes. Add the stewed tomatoes, tomato puree, chicken stock, dry basil, dried rosemary, salt and black pepper to pot.
Working in batches, puree in a blender until smooth. Pour back into pot and adjust seasonings to taste and add milk, if using. Bring soup back up to serving temperature. Sprinkle with freshly chopped basil.