In a large frying pan, brown the Italian sausage with the onion over medium-high heat (4-5 minutes). Add minced garlic and cook 1 minute.
Add the sausage mixture, broth, potatoes, salt, pepper, and pepper flakes to the Slow Cooker (4-6 quarts).
Cook on Low for 4-5 hours or High for about 2 hours (cooking times vary by slow cooker).
Once potatoes are tender, stir in kale, cream, and Parmesan.
Taste and adjust seasonings as desired.
