1Beat eggs, salt and pepper in medium bowl with fork or wire whisk until well mixed. Stir in cheese; set aside.
2Melt butter in ovenproof 10-inch nonstick skillet over medium heat. Cook bell peppers and onion in butter, stirring occasionally, until onion is tender. Pour egg mixture over pepper mixture. Cover and cook over medium-low heat 8 to 10 minutes or until eggs are set and light brown on bottom.
3Set oven control to broil. Broil frittata with top 4 to 6 inches from heat about 2 minutes or until golden brown. Cut into wedges.