In a large soup pot, heat the onion, shallot, and garlic for about 5 minutes. You can add olive oil if you want to coat the pan first, I never do.
Add the potato, carrots and broccoli along with the vegetable broth. Bring to a boil, and then simmer for 15 minutes.
Meanwhile, in a high-powered blender, combine the cashews with 1 c. water and the nutritional yeast. Blend fully and set aside.
Using an immersion blender (or the blender you just used for the cashews), blend the soup to your desired consistency (I like it fully blended, you decide).
Then pour in the cashew cream, heat through, and serve.