1Beat all ingredients except ham, butter and onion thoroughly with fork or wire whisk until well mixed. Stir in ham.
2Melt butter in 10-inch nonstick skillet over medium-high heat. Cook onion in butter 4 to 5 minutes, stirring frequently, until crisp-tender; reduce heat to medium-low.
3Pour egg mixture into skillet. Cover and cook 9 to 11 minutes or until eggs are set around edge and light brown on bottom. Cut into wedges.