In a large soup pot over medium heat, add the sausage, breaking it up as it cooks. The sausage should contain enough fat to keep it from sticking, but you can add a drizzle of olive oil if it sticks. It's okay if the bottom of the pot gets a little brown. Cook for 3-4 minutes.
Add in the onion and saute for 3-4 minutes, until soft. Add garlic and cook for 1 additional minute. The sausage should be fully brown by this point.
Add the potatoes, chicken broth, parmesan rind, Italian seasoning, and salt. Bring to a boil, cover, and reduce to a simmer. Simmer for about 10 minutes.
Add in the kale, stir, cover again, and simmer for 5 minutes.
Test to see if the potatoes are tender by sliding a fork into one. The potatoes should be easily pierced by the fork. Add in the heavy cream and red pepper flakes, stir, and simmer for 1-2 additional minutes.
Remove from heat, ladle into bowls, and serve with freshly shaved parmesan cheese and fresh cracked pepper. Enjoy!