When the tomatoes are tender, remove the cheesecloth packet from the soup. Purée the soup in a blender.
Place a coarse strainer over a bowl. Pour the soup into the strainer in several batches, stirring with a wooden spoon. Discard the soup solids.
Transfer the soup to the Dutch oven. Add the remaining ingredients, including the remaining 2 tablespoons butter; stir until the butter melts and the soup is heated through. Season to taste.
Top each serving with a pastry round.
This soup will keep for up to 3 days in a covered container in the refrigerator. The puff pastry is best when baked just before serving.