Cut cauliflower into rough florets and chop onion. Heat coconut oil in a large pot on medium heat. Add onion and sauté for 2-3 minutes until starting to turn translucent. Add garlic and sauté a minute longer.
Add cauliflower and broth and bring to a boil. Turn head down to medium-low and simmer with the lid on for 20 minutes or until cauliflower is soft. Add spinach, parsley, lemon juice, cayenne, and Purée with an immersion blender until smooth (2-3 minutes usually). Add salt and pepper to taste and adjust other seasonings (cayenne and lemon) if desired.
Garnish with parsley, a sprinkle of cayenne, olive oil, and/or hot pepper sauce if desired.