Peel and core apple; cut into 1/8-inch thick slices. Set aside.
In a 10-inch skillet with all metal handle (or handle covered with heavy duty foil), over medium low heat, melt butter (do not use margarine because is separates from sugar during cooking). Stir in cinnamon and 1/4 cup sugar; remove skillet from heat.
In butter mixture in skillet, arrange apple slices, overlapping them slightly. Repeat with smaller circle of apple slices in center.
Return skillet to low heat; cook 10 minutes or until apples are tender crisp.
Meanwhile, preheat oven to 400°F In medium bowl, with fork beat flour, milk, baking powder, salt, and egg yolks until blended; set aside.
In small bowl, with mixer at high speed, beat egg whites and remaining 1/3 cup sugar until soft peaks form. With rubber spatula, gently fold egg-white mixture into egg yolk mixture.
Cover apple slices in skillet with egg mixture; with rubber spatula, spread batter evenly.
Bake pancake 10 minutes or until golden brown. Remove skillet from oven. Carefully invert dessert onto large platter to serve. 8 servings.