Line two cookie sheets with parchment paper. Generously spray with cooking spray. On one cookie sheet, place the diced carrots and parsnips. On the other cookie sheet, place the sweet potatoes, celery root, and rutabaga.
Place both sheets in the oven and roast vegetables until tender, around 45 or so minutes. The sheet with the carrots may be done first, so check once in a while.
When all the vegetables have finished roasting, remove from the oven and carefully transfer to a blender or food processor. Add the remaining ingredients. Process until smooth and very velvety.
To Prepare Walnut Croutons:
Preheat oven to 375. Combine walnuts with all the ingredients.
Spread on baking sheet and bake 10-15 minutes, or until golden brown and fragrant.
To Prepare Crispy Parsley Garnish:
Clean and shred parsley.
Heat a skillet and spray with cooking spray. Let parsley crisp in the pan until reached desired level of crispiness- but keep an eye on it, since it burns easily!
To Serve
Spoon soup into bowls, top with walnut croutons and sprinkle with the crispy parsley. Add a sprinkle of cinnamon or cayenne for extra colour.