01 - Heat olive oil in a large soup pot over medium heat. Add the Italian sausage and cook until browned on all sides, breaking it into bite-sized crumbles with a wooden spoon, approximately 6 to 8 minutes. Drain any excess rendered fat if necessary.
02 - Add the chopped onion to the pot and sauté until softened and translucent, about 5 minutes. Stir in the minced garlic and continue cooking for 1 minute until fragrant.
03 - Add the sliced potatoes to the pot and pour in the chicken broth. Bring the mixture to a rolling boil, then reduce the heat to medium-low. 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 the leaves are wilted and vibrant green.
05 - Reduce the heat to low and slowly stir in the heavy cream. Season with salt, black pepper, and crushed red pepper flakes if desired. Simmer gently for an additional 2 to 3 minutes to allow the flavors to meld together.
06 - Taste the soup and adjust the seasoning as needed. Ladle into bowls and serve hot, accompanied by crusty bread if desired.