In a medium mixing bowl, beat sugar and eggs lightly. In a separate bowl, toss flour and baking powder with fork. Add milk, vanilla, remaining flour, mix until batter is smooth. Pour into prepared pan. Core and cut apples in eighths, or smaller for very large apples.
Place apples on top of batter with rounded side up.
Sprinkle with cinnamon sugar mixture. Bake 35-40 minutes or until toothpick inserted in center comes out clean. Cool 10 minutes on rack, remove from pan. 12 servings . Wilton products can be found in craft, department, party and specialty stores.