In a skillet over medium heat, brown the ground Italian sausage until cooked through. Make sure to break it into small pieces as it cooks. Drain excess fat and set the cooked sausage aside.
In the crockpot, combine the cooked sausage, chopped onion, minced garlic, cauliflower florets, chicken broth, and red pepper flakes.
Cover the crockpot and cook on low heat for about 4-6 hours, or until the cauliflower is tender.
30 minutes before serving, stir in the chopped kale and unsweetened almond milk. Let it continue to cook until the kale is wilted and the flavors are well combined.
Taste and season with salt and pepper as needed. The sausage and broth might already contain some salt.
Ladle the soup into bowls and top with grated Parmesan cheese if desired.