Preheat the Oven and Prepare the Pan: Preheat the oven to 350°F (175°C). Lightly grease a 9 × 5-inch loaf pan and line it with parchment paper, leaving some overhang along the long sides for easy removal.

Position an oven rack in the center of the oven to encourage even baking.

Mash the Bananas: Peel the ripe bananas and mash them with a fork until mostly smooth. A few small lumps are fine, but avoid leaving large chunks that could create wet pockets in the finished loaf.

Measure out exactly 1 cup (225 g) of mashed banana.

Combine the Wet Ingredients: In a large mixing bowl, whisk together the mashed banana, pumpkin puree, vegetable oil, and brown sugar.

Add the eggs and vanilla extract: Whisk until the mixture looks smooth and evenly blended, with no visible streaks of egg.

Mix the Dry Ingredients: In a separate medium bowl, whisk together the all-purpose flour, baking powder, baking soda, kosher salt, cinnamon, ginger, and nutmeg.

Mix thoroughly so the leavening agents and spices are evenly distributed throughout the flour.

Make the Batter: Add the dry ingredients to the wet mixture. Fold gently with a rubber spatula until no dry flour remains.

The batter should be thick, moist, and easily spreadable rather than pourable. Stop mixing as soon as the ingredients are combined. A few small lumps are preferable to an overmixed batter.

Fill the Loaf Pan: Transfer the batter to the prepared loaf pan and spread it into an even layer.

If using the optional turbinado sugar, sprinkle it evenly over the surface. This creates a lightly crunchy, golden topping.

Bake the Pumpkin Banana Bread: Place the pan on the center oven rack and bake for 55–65 minutes.

The loaf should rise into a gently domed shape, develop a deep golden-brown crust, and begin to pull slightly away from the sides of the pan.

Insert a toothpick or wooden skewer into the center. It should come out clean or with a few moist crumbs, but no wet batter.

If the top is browning too quickly before the center is done, loosely cover it with aluminum foil for the remaining baking time.

Cool in the Pan: Remove the bread from the oven and place the pan on a wire rack.

Let it cool in the pan for 15 minutes. This short resting period helps the loaf firm up so it is less likely to break when removed.

Remove and Cool Completely: Use the parchment overhang to lift the loaf out of the pan. Transfer it directly to the wire rack.

Allow it to cool for another 45 minutes before slicing. Cutting the bread while it is very hot can compress the soft crumb and make the center appear gummy.

Slice and Serve: Once the loaf has cooled, cut it into 10 even slices using a serrated knife.

Serve plain, lightly toasted, or with a little butter. The pumpkin and banana flavors become more pronounced as the bread rests.