Ingredients

• Cooking spray
• 3/4 cup walnut pieces (optional)
• 8 tablespoons (1 stick) unsalted butter, melted
• 1 1/2 cups all-purpose flour
• 1 tablespoon pumpkin pie spice
• 2 teaspoons baking powder
• 3/4 teaspoon kosher salt
• 1/4 teaspoon baking soda
• 2 very ripe medium bananas (3/4 cup mashed)
• 1 large egg
• 3/4 cup pumpkin purée
• 1/2 cup granulated sugar
• 1/2 cup packed dark brown sugar
• 1 tablespoon vanilla extract

1. Arrange a rack in the middle of the oven and heat the oven to 350°F. Coat a 9x5-inch loaf pan with cooking spray.
2. If using walnuts, spread 3/4 cup walnut pieces on a rimmed baking sheet. Bake until fragrant and lightly toasted, about 5 minutes. If the pieces are large, transfer to a cutting board and coarsely chop when cool.
3. Whisk 1 1/2 cups all-purpose flour, 1 tablespoon pumpkin pie spice, 2 teaspoons baking powder, 3/4 teaspoon kosher salt, and 1/4 teaspoon baking soda together in a bowl.
4. Mash 2 medium bananas in a large bowl with a fork or potato masher until smooth with just a few small lumps (3/4 cup mashed). Add the melted butter, 1 large egg, 3/4 cup pumpkin purée, 1/2 cup granulated sugar, 1/2 cup packed dark brown sugar, and 1 tablespoon vanilla extract, and whisk until combined.
5. Add dry ingredients to the pumpkin-banana mixture, then stir with a rubber spatula until just incorporated but no dry spots remain. If using walnuts, reserve 2 tablespoons for topping, then fold the remaining into the batter.
6. Pour the batter into the prepared pan and spread into an even layer. Sprinkle with the reserved walnuts.
7. Bake until the bread pulls away from the sides of the pan, the top is cracked, and a toothpick inserted in the center comes out mostly clean with a few moist crumbs attached, 55 to 60 minutes. Let cool 10 minutes in the pan, then flip the bread out onto a wire rack and let cool completely before slicing.