Conventional Method:
Saute diced onion in olive oil. Add milk, chopped cauliflower, stock and stock powder. Cook for 20 - 30 minutes. Put into a food processor or blender and puree. Add Brie and seasonings to taste and puree again.
Top with chopped chives to serve.
Thermomix Method(TM31):
Chop onion on speed 5 for a few seconds. Scrape down and add oil. Saute on 100/speed 2/5 minutes. Add cauliflower, liquid stock, milk and stock paste. Cook on 100/speed 2-3 20 - 30 minutes. Bring slowly up to speed 7 to puree for a few seconds. Add Brie and seasonings to taste, repeat.