Step 1: Preheat your oven to 350°F (175°C) and grease a 9x5 inch loaf pan with butter or non-stick spray.
Step 2: In a large mixing bowl, mash the ripe bananas with a fork or potato masher until smooth.
Step 3: Stir the melted butter into the mashed bananas until well combined.
Step 4: Mix in the granulated sugar, beaten egg, and vanilla extract.
Step 5: Sprinkle the baking soda and salt over the mixture and stir it in.
Step 6: Gently fold in the flour until just combined—be careful not to overmix the batter.
Step 7: Fold in the toasted chopped walnuts.
Step 8: Pour the batter into the prepared loaf pan and smooth the top with a spatula.
Step 9: Bake for 55 to 65 minutes, or until a toothpick inserted into the center comes out clean.
Step 10: Let the bread cool in the pan for 10 minutes, then remove to a wire rack to cool completely.