Coat a large Dutch oven with cooking spray;
add margarine, and place over medium heat
until margarine melts. Add green onions and
garlic; sauté 2 minutes. Add mushrooms; sauté
3 minutes. Sprinkle flour over vegetables; stir
and cook 1 minute. Gradually add broth and next
4 ingredients, stirring with a wire whisk until blended.
Bring to a boil; reduce heat and simmer, uncovered,
5 minutes. Combine cornstarch and water; stir well,
and add to mushroom mixture. Stir in milk; bring
to boil over medium-high heat and cook 1 minute
or until thickened, stirring constantly.
Discard bay leaf. Garnish with parsley, if desired.