Brown the Italian sausage in a skillet over medium heat, breaking it into crumbles. Drain any excess grease.
Transfer the cooked sausage to the crockpot.
Add the onion, garlic, potatoes, chicken broth, water, Italian seasoning, crushed red pepper flakes, salt, and black pepper.
Cover and cook on Low for 6 to 7 hours or High for 3 to 4 hours, until the potatoes are fork-tender.
About 30 minutes before serving, stir in the chopped kale, heavy cream, and half of the cooked bacon.
Cover and continue cooking until the kale is tender.
Serve topped with the remaining bacon and Parmesan cheese, if desired.