01 - Heat olive oil in a large soup pot over medium heat. Add the Italian sausage and cook until browned, breaking it into bite-size crumbles with a spoon, about 6 to 8 minutes. Drain excess fat if needed.
02 - Add the chopped onion to the pot and sauté until softened, about 5 minutes. Stir in the minced garlic and cook for 1 minute until fragrant.
03 - Add the sliced potatoes and pour in the chicken broth. Bring to a boil, then reduce heat and simmer uncovered for 15 to 20 minutes, or until the potatoes are fork-tender.
04 - Stir in the chopped kale and cook for 3 to 4 minutes until wilted and bright green.
05 - Lower the heat and slowly stir in the heavy cream. Season with salt, black pepper, and crushed red pepper flakes if using. Simmer gently for 2 to 3 minutes to allow flavors to meld.
06 - Taste and adjust seasoning as needed. Ladle into bowls and serve hot, accompanied by crusty bread if desired.