1. Melt the butter in a large saucepan over medium heat.
2. Add the chopped onion
3. Cook until onion is slightly brown, about 5 minutes.
4. Place the water in the saucepan with the cooked onion.
5. Add the cheese and stir well.
6. Stir in the salt and pepper
7. Bring to a rapid boil.
8. Continue cooking until cheese is melted and soup of the consistency you desire.