Place the potatoes, onion and water in a large saucepan. Bring to a boil. Reduce heat; cover and cook for 15-20 minutes or until tender. Remove from the heat; cool slightly (do not drain). In a blender, cover and process mixture in batches until smooth. Return all to the pan and heat through., Stir in the milk, beer, Worcestershire sauce, bouillon, salt, mustard and white pepper; heat through. Stir in cheese just until melted. If desired, top with croutons, bacon, chives and/or pepper.