Preheat oven to 350°F and spray a 9x5-inch loaf pan with cooking spray and set aside.
In a large bowl, whisk together flour, soda, and salt and set aside.
In a medium bowl, mash the bananas and whisk in the sugars, yogurt, eggs, and vanilla. Fold in chopped apples and walnuts.
Add the wet ingredients to the dry ingredients and mix just until combined, do not overmix. Add the batter to the prepared baking pan and bake for 1 hour or until toothpick comes clean from the center of the bread.