Cook the Italian sausage and optional red pepper flakes in a Dutch oven over medium-high heat until the sausage is crumbly and browned, 10 to 15 minutes. Drain and set aside.

Cook the bacon pieces in the same Dutch oven over medium heat until crisp, about 10 minutes. Drain, leaving a few tablespoons of drippings with the bacon in the bottom of the Dutch oven. Stir in the chopped onions and minced garlic; cook until the onions are soft and translucent, about 5 minutes.

Stir in the chicken broth and bring to a boil over high heat. Add the cubed potatoes and simmer until fork tender, about 20 minutes.

Reduce the heat to medium; stir in the cream, cooked sausage, and kale. Cook and stir until the kale has wilted and the sausage is warmed through. Serve immediately.