Heat oven to 350°F. Generously grease 13x9-inch (3-quart) baking dish or 12-inch ovenproof skillet. In large bowl, combine eggs, milk, margarine, salt, pepper and nutmeg; beat well. Stir in frozen vegetables, 1 cup of the cheese and onions; mix well. Pour mixture into greased baking dish.
Bake at 350°F. for 25 to 30 minutes or until eggs are just set in center, stirring twice during baking. Sprinkle with remaining 1/2 cup cheese; let stand 2 to 3 minutes or until cheese is melted.