Pour boiling water over the cashews to cover and let rest for 15 minutes. Drain and rinse before using. Meanwhile, prep all the other ingredients (cut cauliflower, herbs, garlic).
Strip the thyme leaves and rosemary leaves from the stems and roughly chop them up.
Heat 1 tablespoon olive oil in a large Dutch oven or soup pot over medium heat. Once hot, add the garlic, thyme, and rosemary, cook for 2-3 minutes, stirring frequently.
Pour in the vegetable broth and deglaze the pot, stirring up any browned bits on the bottom of the pot. Then add the soaked and drained cashews, cauliflower florets, cannellini beans, bay leaf, nutritional yeast, 1 ¾ teaspoons kosher salt, and black pepper to taste. Stir to combine.
Add enough water (or more vegetable broth) to cover the cauliflower and beans.
Bring the soup to a boil. Then reduce the heat to maintain a rapid simmer and cook for 15 minutes, or until the cauliflower is tender and soft.
Once the soup is done cooking, blend it up until thick, creamy, and smooth. You can transfer it to a stand blender (in two batches), or use an immersion blender. If you use a stand blender, remove the center cap of the blender and cover it with a dish towel to allow the steam to escape.
Taste for salt and pepper and adjust accordingly (I usually add a bit more salt at this stage).
Transfer the soup to bowls, and before serving, zest some lemon on top, add a scattering of red pepper flakes, and drizzle with a bit of extra virgin olive oil. Serve with bread, if desired.