In a large soup pot, cook the sausage over medium-high heat. Break it up with a spoon.

Add the chopped onions, salt, and red pepper flakes. Cook for 7-10 minutes, until the sausage is browned.

Stir in the minced garlic and sauté for 1 minute until fragrant.

Turn off the heat and drain excess grease from the pot.

Return the pot to the heat, stir in the flour, and cook for 1 minute.

Slowly add the chicken broth while stirring constantly to prevent lumps.

Gradually add the whole milk, continuing to stir.

Add the sliced potatoes and bring the soup to a low boil over medium heat.

Simmer for 20 minutes, or until the potatoes are fork-tender.

Stir in the chopped kale and mix gently.

Pour in the heavy cream, stirring lightly to avoid breaking the potatoes.

Reduce the heat to low and cook for 15 minutes, until the kale is wilted.

Stir in the Parmesan cheese. Season with additional salt and black pepper to taste.

Ladle the soup into bowls and garnish with extra shredded Parmesan cheese and freshly ground black pepper.