01 - Set oven to 350°F (175°C) to achieve optimal baking temperature.
02 - Grease a 9x5-inch loaf pan with butter or non-stick spray to prevent sticking.
03 - Mix whole wheat flour, baking soda, and salt in a medium bowl until evenly blended.
04 - In a large bowl, whisk together mashed bananas, brown sugar, melted butter, eggs, and vanilla extract until creamy.
05 - Stir dry ingredients into wet mixture until just combined; avoid overmixing. Fold in walnuts if using.
06 - Pour batter into prepared pan, smoothing the surface with a spatula.
07 - Bake for 50-60 minutes until a toothpick inserted in the center emerges clean.
08 - Allow bread to cool in the pan for 10 minutes, then transfer to wire rack to cool fully before slicing.