In 3 quart saucepan, combine potatoes, onions and broth. Bring to a boil, reduce heat to low and cook for 10 minutes or until potatoes are tender.
Transfer soup to a blender and puree. Return blended soup to saucepan and stir in milk, mushrooms, bell pepper and green onions.
Simmer over medium-low heat and add cheese, a few tablespoons at a time, continually stirring to ensure it melts. Season with salt and pepper, sprinkle with parsley and serve.