Heat oil in large ovenproof nonstick skillet on medium heat. Add onion and zucchini; cook and stir 2 minutes. Reduce heat to medium-low. Add ham; cook 2 minutes.
Beat eggs, milk, Italian seasoning, salt and pepper in medium bowl. Pour into skillet. Cook without stirring 5 minutes or until eggs are set on bottom. Arrange sliced tomatoes on top of egg mixture. Sprinkle with cheese.
Broil 4 to 5 minutes until eggs are set and cheese is lightly browned. Sprinkle with additional Italian seasoning, if desired.