Drain the maitake and shiitake mushrooms and reserve the liquid. Chop all the mushrooms. Heat oil over medium flame in a soup pot.
Add mushrooms to pot along with shallot, leek, onion, celery, carrot, and potato. Increase heat to medium-high, and cook vegetables, stirring often, until they begin to soften, about ten minutes.
Add soaking liquid from mushrooms, stock, tamari and bay leaf. Bring to a boil, reduce heat, and simmer 30 minutes.
Add thyme and rosemary, and puree with a vertical hand blender until smooth.
Season to taste and simmer an additional 5 minutes.
Serve in bowls and drizzle optional cognac on top to give it a "French" touch