Preheat the oven to 350°F (176°C). Coat an 8"x8" inch pan with nonstick
Peel, core, and chop the apples.
In a large bowl, whisk together flours, baking soda, cinnamon, and salt.
In another large bowl, whisk together sugar, oil, yogurt, egg, and vanilla extract.
Add the egg mixture to the flour mixture and stir until just combined. Fold in
the chopped apples. Scrape the batter into the prepared pan and spread it out evenly.
Bake for 35 to 40 minutes, or until a wooden toothpick inserted into the center
comes out clean. Remove from the oven and cool in the pan on a wire rack. Cut into
16 even squares and serve warm or at room temperature.