Soak cashews overnight or for 10 minutes in boiling water.
Heat the oil: In a large pot or Dutch oven, heat the olive oil over medium heat. Add the onion and cook until softened, about 5 minutes.
Add the aromatics: Stir in the garlic, cumin, thyme, and cayenne pepper (if using), and cook for an additional minute until fragrant.
(Optional) Roast the chopped cauliflower in a foiled-lined pan and coat with olive oil at 450 degrees for 5 minutes. This will create a richer flavor.
Add the roasted cauliflower to the pot and cook for 5-7 minutes, stirring occasionally, until slightly softened and golden brown in some spots.
Build the base: Pour in the vegetable broth and bring to a boil. Reduce heat, cover, and simmer for 15-20 minutes, or until the cauliflower is very tender.
Blend it smooth: Transfer the soup to a blender along with the soaked cashews and coconut milk. Blend until creamy and smooth, adjusting the thickness with extra broth if needed.
Season and serve: Return the soup to the pot and heat through. Season with salt and pepper to taste. Garnish with a sprinkle of vegan cheese, fresh herbs like parsley or dill, croutons, or a drizzle of olive oil.
