In a large pot, over medium-high heat, add the Italian sausage and cook for 5-6 minutes until browned. Remove from the pot and set aside.

In the same pot, melt 2 tablespoons of butter over medium heat. Add the chopped onion and sauté for 3-4 minutes until translucent. Stir in minced garlic and cook for 1 more minute.

Pour in 6 cups of broth and 2 cups of water. Add sliced potatoes, salt, pepper, and red pepper flakes. Bring to a boil, then reduce heat and simmer for 12-15 minutes until potatoes are tender.

Stir in 4 cups of chopped kale and simmer for about 2-3 minutes until wilted.

Reduce heat and whisk in 2 cups of cream. Stir gently to warm through without boiling.

Return the browned sausage to the pot, stir, and adjust seasoning as necessary. Warm through for 1-2 minutes.

Ladle the soup into bowls and garnish with crumbled bacon and grated Parmesan cheese before serving.