Peel and dice potatoes, and cook in water until tender. Drain potatoes and return to saucepan. Add milk and heat slowly. Do not allow to boil. Add butter, sour cream, bacon, green onion, and cheese. Cook just until butter, sour cream, and cheese are mostly melted. Season with salt and pepper. Serve immediately. Garnish with additional green onions, cheese, and sour cream if desired.