Clean and cut the cauliflower into small pieces. Put an inch of water into a pot that a steamer basket or insert fits into and bring to a boil. Put the cauliflower pieces in the steamer basket and place in the pot. Cover and steam for 6 to 7 minutes, or until cauliflower is tender.
Add the mushrooms and sauté for five minutes, until they are soft and creamy.
This recipe works with cauliflower mash, cauliflower potato mash, and mashed potatoes. However, each kind effects the thickness of the soup. To thin out the soup, just add more broth.