1) Preheat the oven to 200°C / gas mark 6.
2) Arrange the bread cubes on a greased baking sheet and spray with cooking spray. Sprinkle the cubes with the Parmesan cheese. Bake for 10 to 15 minutes, or until golden brown
3) While the croutons are baking, heat the oil in a large saucepan over medium heat. Add the leeks and garlic and cook for two minutes, or until soft. Add the bay leaves and thyme and cook for one minute, or until fragrant. Add the asparagus, potato and stock and bring to a simmer.
4) Reduce the hob heat to medium, partially cover the saucepan and simmer for ten minutes, or until the potato is fork tender. Remove the bay leaves and, using an immersion blender, or a regular blender working in batches, puree the soup until smooth.
Ladle the soup into bowls and top with sun-dried tomatoes and the croutons.
Cook's note: When blending hot liquids, remove the liquid from the heat and allow to cool for at least five minutes. Transfer the liquid to a blender or food processor and fill it no more than halfway. If using a blender, release one corner of the lid. This prevents the vacuum effect that creates heat explosions. Place a towel over the top of the machine, pulse a few times, then process on high speed until smooth.