Finely puree onion and thyme in a blender.
Finely chop all mushrooms in a blender.
Saute the onions in butter and, when brown, add the mushrooms and bay leaves and allow to release their juices (about 10 minutes on hight heat).
Reduce heat to medium and add all remaining ingredients except the cream.
Simmer for 30 mins.
Reduce heat to low and whilst stirring slowly drizzle in the cream.
Simmer for 5 mins and serve immediately.
For vegetarian option replace chicken stock with vegetable stock.
Also can be topped with croutons or a sprinkling of parmesan cheese or crispy fried cubes of bacon.