Bring water to a boil in a large pot.
Add celery and parsley root, onion, potato - all cut in chunks.
Add salt and pepper to taste.
Let them boil for about 15 minutes then add the mushrooms, cut in chunks.
Boil for another 10 minutes and remove from heat.
Meanwhile, preheat the oven at 400 F.
Slice the baguette and brush each slice with some olive oil. Add some mashed garlic cloves on top of each slice and sprinkle with thyme and salt.
Bake them for 15 minutes or until they're crisp.
Now let's get back to the soup. Using a vertical blender, blend well until creamy. Add some yoghurt or sour cream if you want to make it whiter.
Serve with parsley, sour cream and crisp baguette!