Generously coat a 2-quart square baking dish with cooking spray; set aside.
In a medium bowl beat together egg whites, whole eggs, granulated sugar, milk, orange peel, and almond extract with a wire whisk until combined. Blend in yogurt just until smooth. Gradually add flour, beating with whisk until smooth. Pour batter into the prepared baking dish. Sprinkle with cherries.
Bake in a 350 degree F oven for 25 to 30 minutes or until a knife inserted near the center comes out clean. If desired, sprinkle with sifted powdered sugar. Makes 8 servings.