In a large mixing bowl combine the bananas, applesauce and egg; set aside.
In a medium bowl whisk together the flour, sugars, baking powder, baking soda, salt, and cinnamon.
Add the dry mixture to the banana blend alternately with the buttermilk.
Pour the batter into the prepared loaf pan and bake for 45 to 55 minutes. The loaf is done when a toothpick/butter knife inserted in the middle of the loaf comes out clean.
When the pan is cool enough to handle, remove loaf from the pan and cool on a baking rack.