Melt your butter in a large stockpot over medium-high heat.
Add in your diced onions and saute until soft but not browned, about 4 mins. Add in the garlic and saute for 30 seconds more.
Add in your mushrooms and cook over medium-high heat for another 3 mins until softened. Sprinkle in the arrowroot powder/flour and stir with a wooden spoon to combine well.
Pour in the chicken broth, stir well, then bring the mixture to a boil, then add the bay leaf and lower to a simmer for another 15-20 mins.
Remove and discard the bay leaf, then remove the pot from the heat.
Add in the cream/yogurt or milk of your choice and blend using a hand blender/immersion blender until smooth or to your desired consistency. Taste test, add additional cream/yogurt if desired. Sea salt and freshly ground black pepper to taste.
Sprinkle with fresh parsley and thyme, if you like.
Serve hot and Enjoy!