Preheat oven to 350 degrees F. Spray a 9 x 13″ baking dish with cooking spray and set aside.
In a large mixing bowl (I used the bowl of my stand mixer), mash bananas. Add sugars, vegetable oil, eggs, yogurt, and vanilla. Mix with an electric mixer on medium-speed or vigorously by hand until well combined.
Add flours to wet ingredients, and sprinkle baking soda and salt over the flour (not into the wet batter). Stir on low speed or gently by hand until just combined.
Pour batter into prepared dish, and bake in preheated oven for 35 minutes, or until toothpick inserted into center comes out clean. Allow to cool completely before optionally adding frosting and sprinkling with chocolate chips.