Melt the butter in a large pot over medium heat. Mix in the onions and carrots, cooking for 8-10 minutes until tender.
Add the garlic and cook for 1 minute.
Add the tomatoes, sugar, tomato paste, basil, chicken and garlic broths, salt, and pepper and stir well. Bring the soup to a boil for 2-3 minutes.
Lower heat to simmer, and cook for about 30 minutes, until the tomatoes are breaking apart.
Remove from heat and add the cream, stirring into the mixture until fully combined.
Blend the soup ingredients using a handheld blender or food processor.
Serve in deep bowls, topped with croutons, shaved parmesan and chopped basil.