Combine the flours, baking powder and salt in a bowl and stir together with a whisk to combine and set aside. If flour or baking powder is clumpy, be sure to sift it so you don’t end up with any large chunks in your blondies.
Mix together the oil, applesauce and both sugars in a bowl. This allows the sugar to melt a bit and contribute some moisture to the batter which makes it easier to incorporate the other dry ingredients.
Transfer the blondie batter to a 9 x 9 baking dish. Be sure to oil it or spray with some baking spray to prevent sticking. Bake at 350° F for 25-30 minutes or until the blondies look set on top and a toothpick inserted into the center comes out clean.