Preheat the oven to 350°F (175°C). Grease a 9×5 inch loaf pan with butter or non-stick spray.
In a medium bowl, whisk together the all-purpose flour, baking soda, and salt. Set aside.
In a large bowl, cream the softened unsalted butter and granulated sugar together until light and fluffy using a hand mixer or stand mixer.
Add the eggs one at a time to the butter and sugar mixture, beating well after each addition.
Stir in the vanilla extract.
Mix in the mashed ripe bananas until well combined.
Alternate adding the dry flour mixture and the buttermilk to the banana mixture, starting and ending with the flour mixture. Stir just until combined; do not overmix.
Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Bake in the preheated oven for 55 to 65 minutes, or until a toothpick inserted into the center comes out clean.
Remove the banana bread from the oven and let it cool in the pan for 10 minutes.
Turn the bread out onto a wire rack and allow it to cool completely before slicing.