Brown the Italian sausage in a skillet over medium-high heat, breaking it into crumbles, then drain excess fat.
Add cooked sausage, chicken broth, diced potatoes, onion, garlic, red pepper flakes, salt, and black pepper to the slow cooker.
Cover and cook on low for 6 hours or high for 3 hours until potatoes are fork-tender.
Stir in chopped kale and heavy cream, cover and cook on high for an additional 15-20 minutes until kale is wilted.
Serve hot topped with crumbled bacon and additional red pepper flakes if desired.