Preheat your oven to 350 degrees F (175 degrees C) and prepare a 9x5 inch loaf pan with nonstick spray or parchment paper.
Toast the nuts on a dry baking sheet for about 5-7 minutes until fragrant, then set aside to cool.
Cream the softened butter with brown sugar and granulated sugar until fluffy, about 2 minutes.
Add the eggs and vanilla extract to the butter mixture and beat until combined.
Mash the ripe bananas until you have about one cup and stir into the butter mixture.
Add the all-purpose flour and oat flour to the mixing bowl without stirring yet.
Mix together the baking soda, baking powder, and kosher salt, then fold everything together until just combined.