Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 9x5 inch loaf pan.
In a large bowl, sift together the flour, baking soda, baking powder and salt. In a separate bowl, combine the mashed bananas, melted butter, sugar, eggs and vanilla. Stir the banana mixture into the flour mixture just until moistened. Fold in the walnuts. Pour batter into the prepared loaf pan.
Bake for 45 to 55 minutes in the preheated oven, until a toothpick inserted into the center of the loaf comes out clean. Let bread cool in pan for 10 minutes, then turn out onto a wire rack.
Interesting Facts
Banana bread was first created by the American pioneers during the colonial period, when they needed a way to use up overripe bananas.
Banana bread is a classic breakfast and snack food in many countries.
Banana bread is a popular recipe for using up leftover bananas.