Place 1 veal cutlet between 2 pieces of plastic wrap or waxed paper. Working from center, gently pound cutlet with flat side of meat mallet or rolling pin until about 1/8 inch thick; remove wrap. Repeat with remaining cutlets.
Heat oven to 350°F. In pie pan or shallow dish, combine 1/2 cup Parmesan cheese, bread crumbs, oregano and pepper; mix well. Coat each cutlet with flour; dip in eggs. Coat with Parmesan cheese mixture.
Heat oil in large skillet over medium-high heat until hot. Add cutlets; cook 6 to 7 minutes or until golden brown on both sides. Remove from skillet. Arrange cutlets in ungreased 13x9-inch (3-quart) baking dish; sprinkle with mushrooms. Spoon spaghetti sauce over mushrooms. Bake at 350°F. for 25 to 30 minutes or until bubbly.
Meanwhile, cook vermicelli to desired doneness as directed on package. Drain; toss with butter and 1/4 cup Parmesan cheese. Cover to keep warm.
Remove baking dish from oven; sprinkle veal with mozzarella cheese. Serve veal over vermicelli.