In a large pot or Dutch oven, cook the chopped bacon over medium heat until crispy. Remove bacon with a slotted spoon and set aside, leaving the grease in the pot.
Add the Italian sausage to the pot and cook, breaking it up with a spoon, until browned and cooked through. Remove sausage and set aside with the bacon.
In the same pot, add the diced onion and cook until softened, about 3-4 minutes. Add garlic and red pepper flakes (if using), and cook for 1 minute until fragrant.
Pour in the chicken broth and water, then add the sliced potatoes. Bring to a boil, then reduce heat and simmer for 10-12 minutes, or until potatoes are tender.
Stir in the chopped kale and cook for 5 minutes until wilted.
Return the cooked sausage and bacon to the pot. Stir in the heavy cream and season with salt and black pepper to taste. Simmer for another 5 minutes, being careful not to boil.
Serve hot, garnished with grated Parmesan cheese if desired.
Notes
For a lighter version, substitute half-and-half or whole milk for the heavy cream. Store leftovers in an airtight container in the refrigerator for up to 3 days.