In a large pot or Dutch oven, heat a drizzle of olive oil over medium heat. Add the Italian sausage, breaking it into bite-sized pieces. Cook for about 5–7 minutes, until browned and cooked through. Drain excess grease if needed.

Add the diced onion and sauté for 3–4 minutes until translucent. Stir in minced garlic and cook for an additional 1–2 minutes.

Toss the diced potatoes into the pot and pour in the chicken broth. Bring to a gentle boil, reduce heat to low, and cover. Simmer for about 15 minutes, or until the potatoes are tender.

Carefully pour in the heavy cream, stirring gently. Add chopped kale or spinach, stirring until wilted, about 2–3 minutes. Season with salt, black pepper, and optional crushed red pepper flakes.

Ladle soup into bowls and top with freshly grated Parmesan cheese. Optionally garnish with parsley.