1. Heat the olive oil in a large, heavy-bottomed pot over medium heat. Add the Italian sausage, breaking it apart with a wooden spoon. Cook until browned and cooked through, about 6-8 minutes. Remove the sausage with a slotted spoon and set aside, leaving the flavorful drippings in the pot.
2. Add the chopped onion to the pot and sauté until translucent and fragrant, about 5 minutes. Stir in the minced garlic and cook for an additional 1-2 minutes, being careful not to let it burn.
3. Pour in the chicken broth and bring to a gentle boil. Add the thinly sliced potatoes, reduce heat to medium-low, and simmer until the potatoes are tender, about 15 minutes. This is where the soup starts to thicken and develop that comforting body.
4. Return the cooked sausage to the pot, along with the chopped kale and red pepper flakes if using. Let everything simmer together for another 5-7 minutes, until the kale is tender but still vibrant green.
5. Stir in the heavy cream and season with salt and freshly ground black pepper to taste. Heat through for 2-3 more minutes, but do not boil once the cream is added to prevent curdling.
6. Remove the soup from heat and ladle into warm bowls. Top each serving with a generous sprinkle of freshly grated Parmesan cheese.

One tip I’ve learned from countless afternoons cooking alongside Nonna Rosa is to slice the potatoes as thinly as possible. This helps them cook evenly and melt into the broth, creating that silky texture that turns a simple soup into a family favorite. And don’t rush the simmering steps—good things come to those who wait.