Grease a 2-quart square baking dish. In the prepared baking dish combine black beans, enchilada sauce, green chile peppers, green onions, hot pepper sauce (if desired), and garlic. Sprinkle with cheese.
In a medium mixing bowl beat egg whites with an electric mixer on medium speed until soft peaks form (tips curl); set aside.
In a large bowl combine egg yolks, flour, and salt. Using a wire whisk, beat mixture until combined (mixture will be stiff). Gradually whisk in milk until smooth. Fold the beaten egg whites and cilantro into egg yolk mixture. Carefully pour the egg mixture over the bean mixture in baking dish.
Bake in a 325 degree F oven about 45 minutes or until egg mixture appears set when gently shaken. Let stand for 15 minutes before serving. If desired, serve with sour cream, salsa, and additional snipped fresh cilantro. Makes 8 servings.