Preheat oven to 375°. Peel apple, slice thin, sprinkle with sugar and cinnamon; set aside. Beat eggs and milk. Measure flour in medium-size bowl, add egg mixture and whisk until smooth. Melt butter in large iron skillet, add apple slices, saute 1 minute. Pour batter over apple slices and cook to light brown. Place skillet in oven; bake pancake until golden brown, about 10 minutes. Pour on pure maple syrup.