1. Melt butter in a 10-inch ovenproof skillet over medium heat. Add onions and garlic; cook 5 minutes or until tender, stirring occasionally.
2. Arrange onion mixture evenly in bottom of pan. Combine egg substitute and next 3 ingredients; pour evenly over onion mixture. Reduce heat to medium-low; cook, uncovered, 8 minutes or until almost set (mixture will still be wet on top).
3. Preheat broiler.
4. Broil frittata 3 minutes; sprinkle with cheese, and broil 1 minute or until cheese melts. Let stand 5 minutes before cutting into 8 wedges.
carbo rating: 7