Preheat oven to 350 degrees Fahrenheit. Grease and line a 9x13 baking dish with parchment paper, then set aside.
In a medium bowl, whisk together the flours, salt, baking powder, and spices. Set aside.
In the bowl of a stand mixer, cream together the butter and sugars, mixing until light and fluffy.
Add the eggs, one at a time, mixing until fully incorporated.
Add the vanilla extract.
Gradually add the flour mixture, mixing until fully incorporated. The dough will be quite thick at this point, like the consistency of cookie dough.
Remove bowl from stand mixer and stir in the apple chunks.
Spread into the prepared 9x13 baking dish.
Bake for 30-35 minutes, or until golden brown. Be careful not to underbake.
Cool completely before cutting and serving.