Preheat your oven to 350°F and position the rack in the middle. While it heats, grease a 9x5 inch loaf pan thoroughly with butter or cooking spray, paying special attention to the corners and edges. This prevents sticking and ensures even browning on all sides of your finished loaf.

In a large mixing bowl, combine the softened butter and sugar, beating them together until the mixture is pale, fluffy, and resembles wet sand—this usually takes about 2-3 minutes with an electric mixer. This creaming step incorporates air into the batter, which helps create a tender crumb structure. I always make sure my butter is at room temperature before starting, as cold butter won't incorporate air properly and will result in a denser loaf.

Add the room-temperature eggs one at a time to the creamed butter and sugar, beating well after each addition to ensure they're fully incorporated before adding the next. Pour in the vanilla extract and then fold in the mashed bananas gently with a spatula until just combined. The batter should look slightly lumpy at this stage—that's perfect. I like to use very overripe bananas with brown spots because they're naturally sweeter and provide more moisture, which keeps the bread tender and flavorful.

In a separate bowl, whisk together the flour, baking soda, baking powder, cinnamon, and salt. This dry mixture is crucial because whisking distributes the leavening agents evenly throughout the flour, ensuring your banana bread rises uniformly rather than having dense pockets. Keep this bowl ready to add to your wet ingredients.

Pour the dry ingredient mixture from Step 4 into the banana mixture from Step 3 and fold gently with a spatula until just combined—stop as soon as you don't see streaks of flour. The batter will be thick and slightly lumpy, which is exactly what you want. Fold in the roughly chopped walnuts evenly throughout. Overmixing develops the gluten in the flour, which makes banana bread tough and dense instead of tender and moist.

Pour the batter into your prepared pan from Step 1, smoothing the top gently with a spatula for even baking. Place in the preheated 350°F oven and bake for about 1 hour, or until a toothpick inserted into the center comes out clean or with just a few moist crumbs clinging to it. The top should be golden brown and a slight dome may form on top—this is normal.

Remove the banana bread from the oven and let it cool in the pan for exactly 10 minutes—this cooling period allows the structure to set enough to hold together when removed, but it's still warm enough to slide out easily. After 10 minutes, turn the loaf out onto a wire rack or cutting board and let it cool completely before slicing. This prevents the warm bread from crumbling and allows the flavors to fully develop as it cools.