Cook pasta to desired doneness as directed on package. Drain.
Meanwhile, melt butter in large saucepan over medium heat. Add onion; cook and stir 4 to 5 minutes or until tender. Add tomatoes and water; simmer 10 minutes, stirring occasionally. Add cream; simmer 5 minutes.
Add cooked pasta to soup. If desired, add salt and pepper to taste. To serve, ladle soup into individual soup bowls. Top each serving with cheese.