Preheat the oven to 400 degrees F.
Toss all vegetables with the oil, salt, and pepper and spread evenly on a large rimmed sheet pan lined with parchment paper. You may need to use two sheets to avoid overcrowding of the vegetables.
Place in the oven and roast for 30-40 minutes.
Meanwhile, heat vegetable broth, tomato paste, cashews, optional cayenne, and brewers yeast in a large soup pot over medium heat.
Transfer roasted vegetable into the pot and simmer for 5 minutes.
Puree the soup using an immersion blender or carefully transfer to a blender and puree a few cups at a time, until smooth and creamy. Add more water if the soup is too thick.
Season with additional salt and pepper. Add a spoonful of roasted or sautéed chickpeas, sprinkle with freshly chopped parsley or cilantro and enjoy!