Melt butter in saucepan; add onion and celery and cook until tender.
Wash and trim broccoli; cut into small pieces.
In a large saucepan, add broccoli and bouillon.
Bring to a boil; cover and cook over medium heat for 20 minutes.
Stir in onion and celery.
Puree 2-3 batches in blender or food processor.
Return to saucepan, add cream and cook 2 minutes until thickened.
Garnish with chopped scallions.