Preheat oven to 350 degrees F. Coat 3 8-inch round cake pans with cooking spray, and line with parchment paper circles. Spray circles with cooking spray.

To make Ginger Cake: Whisk together whole-wheat pastry flour, cake flour, sugar, cinnamon, baking powder, baking soda, and salt in bowl. Whisk together buttermilk and molasses in separate bowl. Whisk oil, egg, egg whites, and ginger into buttermilk mixture. Fold buttermilk mixture into flour mixture until just combined. Divide batter among prepared pans, and bake 20 minutes, or until toothpick inserted in cake centers comes out clean. Cool in pans 5 minutes, then cool completely on wire racks.

To make Apple Filling: Bring all ingredients to a boil in saucepan over medium heat. Simmer 1 hour, or until apples are jammy and a little syrup remains in pan, stirring occasionally. Cool.

Place one cake layer on serving plate. Spread with half of Apple Filling. Repeat process with second cake layer and top with third layer. Wrap cake in wax paper and then foil to seal, and refrigerate 6 hours, or overnight.

Arrange alternating red and green apple slices in a pinwheel "flower" pattern on top of cake, then dust top of cake with confectioners' sugar.