In a skillet, whisk water with low-sodium soy sauce, 1 tablespoon of nutritional yeast, onion powder, garlic powder, and ground ginger. Bring to a boil and add mushrooms, sprinkling them generously with Italian seasoning (a good 10 shakes). Continue to saute over medium-high heat until the mushrooms are brown and soft, about 3 minutes. Meanwhile, whisk nondairy milk with cornstarch and remaining 1 tablespoon of nutritional yeast. Add a very light dash of nutmeg, if desired. Pour over mushrooms, stirring to combine. Reduce heat to low and continue to cook until thick and gravylike, about 5 minutes. Add black pepper to taste (I like it really peppery) and a few more shakes of Italian seasoning unless you were very generous before. Taste again, adding a pinch of salt if necessary. Set aside for a few minutes before serving to let the flavors merge.
Chef's Note: For a smoky-flavored gravy, substitute smoke paprika for the nutmeg, and add more to taste.