1. Melt butter in saucepan over low heat.
2. Add flour and stir constantly until smooth.
3. Stir in chicken stock and cream until smooth.
4. Add salt, pepper, celery salt, and onion powder.
5. In a separate bowl, beat egg yolks with water and lemon juice and add to cream mixture.
6. Stir in diced chicken to heat for a few minutes and serve with wedges of hot toast or over rice. Serves 4.