Preheat and Prep. Begin by preheating your oven to 350°F. Grease a 9x5-inch loaf pan and set it aside.
Mix the Dry Ingredients. In a medium-sized bowl, whisk together the all-purpose flour, baking soda, baking powder, salt, ground cinnamon, and ground nutmeg. Set this mixture aside for later.
Prepare the Wet Ingredients. In another bowl, combine the mashed bananas and pumpkin puree. These ingredients will add a rich, autumnal flavor and moisture to your bread.
Cream the Butter and Sugar. In a separate large bowl, cream together the softened unsalted butter, granulated sugar, and brown sugar until the mixture becomes light and fluffy. This step is essential for achieving a moist and tender crumb.
Add Eggs and Vanilla. Beat in the eggs one at a time, ensuring each egg is fully incorporated before adding the next. Then, mix in the vanilla extract.
Combine Wet and Dry Ingredients. Gradually add the banana and pumpkin mixture to the butter and sugar mixture, mixing well. Slowly incorporate the dry ingredients, and stir until everything is thoroughly combined. Be careful not to overmix; a few lumps are okay.
Bake to Perfection. Pour the batter into your prepared loaf pan. Bake in the preheated oven for about 60-70 minutes or until a toothpick inserted into the center comes out clean or with a few moist crumbs attached.
Cool and Enjoy. Allow your Pumpkin Banana Bread to cool in the pan for about 10-15 minutes before transferring it to a wire rack to cool completely. Once it's cooled, slice, serve, and savor the flavors of fall.