Preheat oven to 350 degrees F (175 degrees C). Grease a 9x5 inch loaf pan.
In a medium bowl, whisk together the flour, baking powder, baking soda and salt.
In a large bowl, cream together the melted butter and brown sugar. Beat in the eggs one at a time, then stir in the vanilla. Beat in the mashed bananas until blended. Stir in the flour mixture, mixing just until incorporated. Fold in the walnuts and raisins.
Spoon batter into the prepared loaf pan. Bake for 50 minutes in the preheated oven, or until a toothpick inserted into the center of the loaf comes out clean.
Allow bread to cool in pan for 10 minutes, then turn out onto a wire rack.
Interesting Facts
Banana bread was invented in the early 1900s as a way to use up overripe bananas.
Banana bread is a great source of potassium, magnesium, and fiber.
Banana bread can be made with either fresh or frozen bananas.