Preheat oven to 350°F. Grease a loaf pan and set aside.
In a large bowl, stir together dry ingredients.
In a smaller bowl, mash bananas with a fork. Add oil, peanut butter, yogurt, sugar, egg and mix thoroughly.
Add the wet ingredients to the dry and mix well. Batter will be fairly thick.
Pour batter into pan and bake until top of loaf is firm to touch, 45 to 50 minutes. Remove from oven and allow to cool in pan for 5 minutes. Flip out and cool on a wire rack.