Heat olive oil in a large soup pot on medium high. I like cast iron.
Add minced garlic and shallot and stir until nicely browned.
Add onion and saute until translucent.
Add celery and carrots and saute for about 3 minutes.
Add butter and stir to melt into vegetable mixture.
Next add diced mushrooms and stir.
Add dry vermouth and cook and stir for an additional few minutes.
Add the 2 Tablespoons flour and stir to incorporate evenly. Continue to cook for about a minute.
Add 4 cups chicken stock and bring this mixture to a low boil. Turn heat down to simmer and cook, stirring constantly, until all vegetables are tender and soup begins to thicken, about 8 minutes.
Add parsley, salt, pepper and nutmeg.