This soup has a remarkable texture, and is very versatile: you can make it simple, with cauliflower and water instead of stock, or you can use the cauliflower as a base for other flavors.
1 head cauliflower, broken into florets
6c stock, water, or a combination
1 medium onion, chopped
2 cloves garlic, minced
fresh porcini mushrooms for garnish*
*I put a few mushrooms in with the cauliflower but I don't think it added much. Keep them as a topping.
Melt butter in a large pot over medium heat. Add onions and garlic and cook, stirring, about 10 minutes, until very soft. Don't let the onions brown.
Add cauliflower and salt (more if you're using water or no-salt broth). Add liquid to cover; bring to a boil, then simmer gently until cauliflower is soft (about 10 min).
Puree in a blender (I tried using a hand blender but it didn't get the silky consistency) until frothy and smooth.
Slice porcini mushrooms and saute in butter and salt. Serve soup garnished with mushrooms. I sprinkled Aleppo pepper on top as well.