Brown the sausage:
In a large soup pot, heat olive oil over medium heat. Add the Italian sausage, breaking it apart with a spoon, and cook until browned and cooked through. Drain excess fat if necessary.
Sauté the vegetables:
Add chopped onion and garlic to the pot. Cook for 2–3 minutes until fragrant and translucent.
Add potatoes and broth:
Stir in the diced potatoes, Italian seasoning, crushed red pepper, salt, and pepper. Pour in the chicken broth and bring to a boil.
Simmer:
Reduce heat and simmer uncovered for about 15–20 minutes, or until the potatoes are tender.
Make it creamy:
Stir in the heavy cream and grated Parmesan cheese. Continue cooking for 5 more minutes until the soup thickens slightly and becomes creamy.
Add greens (optional):
Stir in fresh spinach or kale right before serving for extra flavor and color.