In a large pot, heat olive oil over medium heat. Add the Italian sausage, breaking it apart. Cook until browned, about 7-8 minutes. Remove sausage and set aside.

In the same pot, add yellow onion and sauté for about 5 minutes until translucent. Add minced garlic and cook for 1-2 minutes until fragrant.

Pour in chicken broth and raise heat to boil. Add sliced potatoes. Reduce to a simmer, cover, and cook for about 15 minutes until potatoes are fork-tender.

Return sausage to the pot, stir to combine with broth and potatoes. Add chopped kale and let simmer uncovered for 5 minutes.

Lower heat and mix in heavy cream. Season with salt, black pepper, and red pepper flakes. Heat gently for 3-4 minutes.

Ladle soup into bowls and top with grated Parmesan cheese. Serve immediately.