Remove the sausage from its casings, chop the bacon into 1/2-inch pieces, finely dice the onion, mince the garlic, slice the potatoes 1/4 inch thick, and chop the stemmed kale into bite-sized pieces.
Cook the chopped bacon in a Dutch oven over medium heat for 6 to 8 minutes until browned and crisp, then remove with a slotted spoon to a paper towel-lined plate, leaving the drippings in the pot.
Add the sausage to the bacon drippings, break it into small crumbles, and cook for 7 to 9 minutes until deeply browned and no longer pink, then spoon off all but about 2 tablespoons of fat.
Stir in the onion and cook for 4 to 5 minutes until soft and translucent, then add the garlic and red pepper flakes and cook for 1 minute until fragrant.
Pour in the chicken broth and scrape up the browned bits, add the sliced potatoes, salt, and black pepper, and bring to a boil over high heat.
Reduce the heat to medium-low, partially cover, and simmer for 15 to 20 minutes, stirring once or twice, until the potatoes are tender but still hold their shape.
Stir in the chopped kale a handful at a time, letting each wilt before adding more, and simmer for 3 to 5 minutes until tender and bright green.
Reduce the heat to low, slowly stir in the heavy cream, warm for 2 to 3 minutes without boiling, then stir in about two thirds of the crispy bacon and reserve the rest for topping.
Taste and adjust the salt, black pepper, or red pepper flakes, ladle into warm bowls, and top each with grated Parmesan and the remaining crispy bacon.