Prepare a 9"loaf pan with butter and flour (or pan spray).
Preheat the oven to 325 degrees F.
Add the all-purpose flour, salt, baking soda, and baking powder to a small bowl. Whisk the dry ingredients together until well blended
Add the melted butter and sugar to a large bowl. Mix until well combined.
Add the eggs one at a time and whisk until completely blended into the mixture.
Mash the bananas.
Add the mashed bananas to the wet ingredients and mix until well combined.
Add the raisins, walnuts, and vanilla extract and mix until well combined.
Add the flour mixture to the wet ingredients one-third at a time. mixing until each addition is just mixed in. Don't overmix.
Pour the batter into the prepared loaf pan.
Place the loaf pan on the center rack of the preheated oven and bake for 60-70 minutes or until a toothpick inserted into the center of the banana bread comes out clean.
Place the pan on a rack to cool for 15 minutes.
Remove the banana bread from the pan and serve warm.