In a large skillet, cook bacon until crisp. Drain, reserving 1 tablespoon drippings. Set bacon aside. Saute onions in drippings until tender; set aside, In a bowl, beat eggs. Add the milk, seasoned salt, 2 cups of the cheese and sauteed onions. Transfer to a greased shallow 2-qt. baking dish.
Bake, uncovered, at 350º for 35-40 minutes. Sprinkle with the remaining cheese.