Preheat oven to 400° F. Spray a 9x9 inch baking dish with cooking spray.
In a large bowl, whisk eggs and milk until combined. Stir in cheese and ham. Pour mixture into the prepared baking dish.
Bake, uncovered, for 25 minutes or until golden brown and cooked through. Remove from oven. Let stand 5 minutes before slicing and serving. Serve with chives, if desired.
Notes
This recipe easily doubles. Use a 9x13 inch baking dish when doubling.