Place the basil leaves and the Parmesan cheese and stewed tomatoes into a blender. Puree on high (30 seconds) or until the basil shows as specks in the soup. Set aside.
Meanwhile, heat olive oil in 3qt pot. Add onions, garlic and oregano and saute for 3 or 4 minutes. Don't let the garlic burn. Add basil, tomato paste and tomato mixture and chicken broth to pot. Bring to a slow simmer for 20 minutes.
Serve with a generous amount of Parmesan cheese over the soup and some chopped basil. This soup is great with some nice garlic bread. Easily made with a French baguette split down the middle, buttered, sprinkled with garlic powder and topped with Parmesan cheese, then under the broiler for about 3 or 4 minutes. Voila!