In a large pot, heat the olive oil over medium heat. Add the Italian sausage and break it apart as it cooks, browning for about 7-8 minutes before transferring it to a plate, leaving some fat in the pot.
Next, add the chopped onion, carrots, and diced celery to the pot. Sauté for 5 minutes until they soften and turn fragrant.
Stir in the minced garlic, Italian seasoning, crushed red pepper flakes, and tomato paste. Cook for an additional minute, allowing the flavors to meld and the tomato paste to deepen in color.
Pour in the chicken broth, scraping the bottom of the pot to release any browned bits. Add the white beans and sun-dried tomatoes, then bring to a gentle simmer. Allow to cook for about 10-15 minutes.
Add the chopped kale back into the pot along with the reserved sausage. Cook for an additional 5 minutes, or until the kale is tender and the soup thickens slightly. Season it with salt and pepper to taste.
Serve hot, garnished with chopped parsley and a generous sprinkle of Parmesan cheese. Pair with crusty bread for a satisfying meal.