Preheat oven to 400 F (200 C). Grease muffin tins. core,slice and mince the apple(use food pocessor if you have). Set aside. In a large bowl,mix together the flour,oatmeal,baking powder and baking soda. In a medium bowl,blend together the yogurt,water,oil,honey and eggs.Stir in the apple and cheese.Add to the flour mixture and stir until mixed. Spoon into the muffin tinsfilling each cup about three-quarters full. Bake for about 20 minutes or until a toothpick inserted in the center of a muffin comes out clean. Let rest in the muffin tins for a few minutes, then remove and set aside to cool. For the frosting, combine the Neufchatel cheese (at room temperature), honey, and yogurt until smooth. Add enough flour to thicken the frosting to a good spreading consistency. Frost the pupcakes and you're ready for a doggone good party! Makes 16-18 pupcakes. If you prefer a single-layer cake, spoon the batter into a sheet pan and bake for an extra 15-20 minutes (or until a toothpick inserted in the center of the cake comes out clean). Let the cake cool, then frost and decorate.