Brown the sausage: Set a large pot over medium-high heat. Add the sausage and cook, breaking it into small pieces, until browned and cooked through, 6–8 minutes.
If there’s excess fat, spoon off all but about 1 tablespoon.
Sauté aromatics: Add olive oil if the pot looks dry. Stir in the onion and cook until softened and lightly golden, 4–5 minutes. Add garlic and cook 30 seconds, until fragrant.
Boost the base: Stir in tomato paste, Italian seasoning, and red pepper flakes.
Cook 1 minute to caramelize the paste slightly.
Add broth and potatoes: Pour in the chicken broth and bring to a boil. Add the potatoes, reduce to a simmer, and cook until the potatoes are tender, 12–15 minutes.
Stir in kale: Add the chopped kale and simmer until wilted and tender, 3–5 minutes. If you prefer very soft kale, give it a couple more minutes.
Finish with cream: Reduce heat to low.
Stir in the heavy cream and season with salt and black pepper. Taste and adjust seasoning as needed.
Serve: Ladle into bowls and top with Parmesan if using. Serve with crusty bread for dipping.