In a 12-inch skillet cook mushrooms and green onion in 2 teaspoons of the hot margarine or butter for 4 to 5 minutes or until tender. Remove from skillet; set aside.
Meanwhile, cut veal into 2 serving-size pieces. Place one piece of veal or one chicken breast between 2 sheets of clear plastic wrap. Working from center to edges, pound lightly with the flat side of a meat mallet to about 1/8-inch thickness. Remove plastic wrap. Repeat with remaining veal or chicken.
Sprinkle meat with salt and pepper. In the same skillet cook veal or chicken in the remaining hot margarine or butter over medium-high heat about 1 minute on each side or until light brown. Transfer to warm dinner plates; keep warm.
Add Marsala or sherry and chicken broth to drippings in skillet. Bring to boiling; boil gently, uncovered, about 1 minute, scraping up any browned bits. Return mushroom mixture to skillet; add parsley. Heat through.
To serve, spoon the mushroom mixture over meat. Serve immediately. Makes 2 servings.
Double this recipe to serve 4, but cook the meat half at a time.