Cook broccoli in large pot of boiling salted water until tender but still bright green, about 5 minutes. Drain broccoli. Set aside 4 small florets for garnish.
Combine broth and 1 cup cream in heavy large saucepan and bring to boil. Working in batches, puree broccoli, broth mixture, and butter in blender until smooth, about 45 seconds per batch. Return puree to same pan. Season soup to taste with salt and white pepper. (Soup can be made up to 8 hours ahead. Cool slightly, cover, and refrigerate.)
Bring soup to simmer, thinning with water if desired. Serve with a drizzle of cream and reserved florets as garnish.
Appeared in print on 1/13/10