Wash the mushrooms to remove any dirt or debris. Slice the mushrooms and mince the garlic.
Add the olive oil, mushrooms, and a pinch of salt and pepper to a soup pot. Sauté the mushrooms over medium heat until they have released all of their moisture, all the liquid has evaporated from the bottom of the pot, and the mushrooms become very dark brown. Add the minced garlic and continue to sauté for one minute more.
Add the butter and flour to the pot. Stir and cook for about two minutes more, or until the butter coats the bottom of the pot and turns deep golden brown.
Once the flour mixture is a bit browned, add the vegetable broth, soy sauce, and thyme. Stir to dissolve all of the flour from the bottom of the pot. Allow the liquid to come up to a simmer, at which point the flour will slightly thicken the broth.
Finally, stir the cream into the soup. Give the soup a taste and adjust the salt or pepper to your liking. Serve with crusty bread and enjoy!