Preheat your oven to 350°F (180°C) and grease a 9x5 inch loaf pan.
In a medium bowl, whisk together the dry ingredients: flour, baking powder, baking soda, cinnamon, and salt. Set aside.
In another bowl, mash the ripe bananas until smooth. Stir in the melted butter, buttermilk, and vanilla extract until well combined.
Add the brown sugar and mix until incorporated.
Gently fold the dry ingredients into the wet ingredients until just combined. Don't overmix! A few lumps are okay.
Fold in the chopped pecans or your chosen alternative.
Pour the batter into the prepared loaf pan. Sprinkle the turbinado sugar and chopped nuts over the top.
Bake for 55-65 minutes, or until a toothpick inserted into the center comes out clean.
Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.