To make the soup, heat the olive oil in a small saucepan over a medium heat, add the spring onions and sweat for 2 minutes or until softened.
Add the fresh parsley, stock and watercress and simmer for five minutes.
Add the cream, season, to taste, with salt and freshly ground black pepper and simmer for another minute.
Blend with a hand blender until smooth and pour into a bowl.
To make the crostini, preheat the grill to high. Rub the olive oil onto the ciabatta bread and top with the Tallegio slices. Season, to taste, with black pepper and place under the grill for 2-3 minutes, until melted and just turning golden-brown.
To serve, place the bowl of watercress soup onto a large plate with the crostini placed alongside.
