Preheat oven to 375 degrees. Unroll crescent rolls, and place in an ungreased 13 by 9 inch pan. Press 1/2 inch up on sides to form a crust; make sure to seal the rolls. Bake for 5 minutes on the lower rack; set aside. Cook onion in butter in a small skillet over medium heat, stirring constantly, until crisp-tender; stir in ham cook until warm through. Once ham is warm spoon evenly over dough. Sprinkle with cheese. Combine eggs , milk, and salt and pepper to taste. Pour over cheese, and sprinkle with chives. Bake for 25 to 30 minutes or until set. Serve immediately.