In a large pot (5 quarts) over medium heat, add the olive oil and cook the onion and garlic for 2-3 minutes, stirring frequently until the onion is soft and the garlic is fragrant.
Pour in the cans of diced tomatoes, tomato sauce and chicken broth
Season with salt and pepper
Bring the soup to a boil and blend with an immersion blender until smooth.
Remove from the heat and stir in the cream and fresh basil.
Notes
If you don't own an immersion blender, the soup can be smoothed in a blender. Pour the soup in batches into the blender, blend with the spout open on the blender to release stem and blend until smooth.