
In a saucepan, saute onions in butter until tender. Stir in flour and salt until blended. Gradually add broth. Bring to a boil; cook and stir until thickened, about 2 minutes. Reduce heat.
Add cauliflower; simmer for 2 minutes. Add the milk and cheese; cook and stir until cheese is melted. Stir in sherry if desired. Garnish with chives.