Soak cashews for a couple of hours or boil them for 15 minutes in water until they are soft.
Preheat oven to 400 degrees Fahrenheit (200 degrees Celsius).
Cut the cauliflower into florets, spread on a baking tray (lined with parchment paper) and drizzle with 1 tablespoon oil and a little salt. Toss with your hands and roast the cauliflower in the oven for about 30-35 minutes until nicely browned and tender. Set aside a few cauliflower florets for garnish.
In a blender, combine all ingredients (add the broth & milk in batches if necessary) and blend until completely smooth.
Taste the soup and adjust seasonings. If you prefer a spicy soup, add some hot pepper flakes!
If the cauliflower soup is too thick (it does get thicker as it sits), add a little bit more broth or plant-based milk and blend again.
Transfer to a pot and warm to the desired temperature.
Garnish with fresh parsley and the reserved cauliflower florets. Enjoy!