In a blender, process tomatoes, one can at a time, until smooth. Transfer to a large saucepan. Stir in the broth; bring to a boil. Reduce heat; cover and simmer for 10 minutes. Stir in the oregano and sugar. Add a small amount of hot tomato mixture to whipping cream; return all to the saucepan. Cook until slightly thickened (do not boil)., If desired, cut snowflake shapes from sliced cheese using small cutter; arrange on top of crackers. Place soup into serving bowl; top with crackers and cheese.