01 - Heat olive oil in a large soup pot over medium heat. Add the sausage, breaking it into crumbles with a wooden spoon. Cook until evenly browned, approximately 5 minutes. Transfer the sausage to a plate and set aside.
02 - In the same pot, cook the diced onion until translucent, 3 to 4 minutes. Add the minced garlic and stir for 1 minute until fragrant.
03 - Add the sliced potatoes and chicken broth to the pot. Bring to a boil, then reduce heat and simmer uncovered for 12 to 15 minutes until the potatoes are just tender when pierced with a fork.
04 - Return the browned sausage to the pot along with the chopped kale. Simmer for an additional 5 minutes until the kale has wilted and softened.
05 - Reduce heat to low. Stir in the heavy cream and season with red pepper flakes, salt, and black pepper to taste. Heat through gently, but do not allow the soup to boil.
06 - Ladle the soup into bowls and garnish with grated Parmesan cheese if desired. Serve with crusty bread alongside.