01 - Set oven to 350°F. Prepare a 9x5-inch loaf pan by greasing it with butter or nonstick spray.
02 - Combine all-purpose flour, baking soda, salt, and pumpkin pie spice in a large bowl. Whisk until evenly distributed.
03 - In a medium bowl, blend pumpkin puree, mashed bananas, melted butter, brown sugar, eggs, and vanilla extract until smooth.
04 - Gently fold wet ingredients into dry mixture until just combined. Avoid over-mixing to maintain bread texture.
05 - Incorporate chopped walnuts into the batter, if using.
06 - Pour batter into prepared loaf pan, spreading evenly.
07 - Place pan on center rack. Bake for 55 to 65 minutes or until a toothpick inserted in the center comes out clean.
08 - Allow bread to cool in pan for 10 minutes. Transfer to wire rack to cool completely before slicing.