Heat a large soup pot or Dutch oven over medium heat. Add the sausage, breaking it up with a wooden spoon as it browns. Cook until it’s fully browned and cooked through, about 7–8 minutes. If it’s lean, add a bit of olive oil to prevent sticking.
Once the sausage is browned, add diced onion to the pot. Cook for 4–5 minutes until softened. Stir in the minced garlic and red pepper flakes and cook for another 30 seconds until fragrant.
Pour in the chicken broth and stir well, scraping any flavorful bits from the bottom. Add the diced potatoes, thyme, smoked paprika, and a generous pinch of salt and pepper. Bring to a boil, then reduce to a simmer.
Let the soup simmer gently for about 15–20 minutes, or until the potatoes are fork-tender. Stir occasionally and check for seasoning—adjust salt and pepper if needed.
Stir in the chopped kale and simmer for another 5 minutes until it’s tender but still vibrantly green. If you prefer kale very soft, let it go for a few extra minutes.
Turn off the heat and stir in the heavy cream for added richness. This step is optional but adds a beautiful silkiness to the soup. Serve hot with a sprinkle of Parmesan and a side of crusty bread.