PREP: Line a slow cooker (5 quarts or larger) with one Reynolds Kitchens® Slow Cooker Liner. Set aside.
COOK MEAT: Heat a large cast iron skillet over medium-high heat. Add the sausage. Let cook without touching for 30 seconds to a minute to get a nice browning and then use a wooden spoon to break it up and continue to cook until nicely browned through. Transfer the sausage to the slow cooker OR to a paper towel lined plate to slightly drain off grease if desired. To the same pot, add in the diced onions. If needed add a drizzle of olive oil (if there wasn't a lot of grease left from the sausage). Cook, over medium-high heat, stirring until softened and tender, about 4–5 minutes. Add the garlic and stir until fragrant, about 30 seconds to a minute. Add right on top of the sausage.
POTATOES: Peel and dice potatoes into 1/2-inch pieces and then add in an even layer right on top of the sausage, onion and garlic. Press all the ingredients into an even layer and then cover with chicken stock. If all ingredients aren't completely covered, add water until they are (up to 1 cup total).
COOK: Cover and cook on LOW for 5-6 hours or HIGH for 3-4 hours or until potatoes are fork tender. Before the soup is finished, wash the kale and remove it from the stem. Dice it and pack into a measuring cups to get 2 cups total. Stir into the soup along with the heavy cream, red pepper flakes, thyme, and seasonings to taste (I add 1/2 teaspoon salt and heaping 1/4 teaspoon pepper, add to preference, remembering that bacon and Parmesan add a good amount of saltiness). Let cook for 15 more minutes and then taste and adjust any seasonings. While it’s finishing cooking, cook the bacon in a skillet until it’s reached desired crispiness. Drain onto a paper towel-lined plate and serve alongside the soup.
SERVE: Serve with desired toppings: freshly grated Parmesan cheese (grate on a microplane for the best texture!) and a crusty toasted baguette or bread. Sprinkle bacon on top of the soup and enjoy.