Heat 1 cup water to boiling in 3-quart saucepan.
Add broccoli, celery, onion and lemon juice.
Cover and heat to boiling; reduce heat.
Simmer until vegetables are tender, about 15 minutes; do not drain.
Place broccoli mixture in blender container.
Cover and blend on medium speed, stopping blender frequently to scrape sides, until mixture is of uniform consistency, about 45 seconds.
Heat margarine in same saucepan over low heat until melted.
Blend in flour.
Cook, stirring constantly, until mixture is smooth and bubbly; remove from heat.
Stir in 1 1/2 cups water.
Heat to boiling, stirring constantly.
Boil and stir 1 minute.
Stir in broccoli mixture, bouillon, salt and nutmeg.
Heat just to boiling.
Stir in chicken and half-and-half.
Heat just to boiling.
Garnish each serving with yogurt, sour cream or lemon slice if desired.
Food Processor Directions: Place broccoli mixture in workbowl fitted with steel blade.
Cover and process until mixture is of uniform consistency, about 15 seconds.