Spray a 13x9 inch baking dish with nonstick cooking spray. Sprinkle half of the cheese evenly into the baking dish.
Mely butter in medium skillet. Add onions and bell pepper. Cook until tender. Put vegetables over cheese in the baking dish. Sprinkle remaining cheese over the vegetables.
Beat eggs in a large bowl. Add flour, parsley, and milk to the eggs. Blend well.
Bake at 350 degrees for 55 minutes or until the mixture is set on top. Let it sit for 10 minutes before serving.