Bring a large soup pot to medium heat. Cook and crumble sausage in pot until it is fully cooked. Remove sausage and set aside. Drain out oil but leave behind about 1 tbsp. Add in diced onions and cook until soft and translucent.
Add in broth and bring soup to a simmer. Add in cauliflower and sausage and cook until cauliflower is soft. Add in red pepper flakes and season with salt. Add in heavy cream. Taste and adjust seasoning as needed.
Add in kale and cook until kale is just tender. Remove soup from heat. Serve soup while still warm.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.