Preheat your oven to 350°F (175°C). This ensures that the banana bread bakes evenly.

Grease a 9x5 inch loaf pan with butter or non-stick spray to prevent sticking.

In a large mixing bowl, mash the ripe bananas with a fork until smooth. This releases the natural sugars and flavors.

Add the softened butter and granulated sugar to the mashed bananas. Mix well until combined.

Add the eggs one at a time, mixing well after each addition. This helps to incorporate air for a lighter texture.

Stir in the sour cream and vanilla extract until the mixture is smooth.

In a separate bowl, whisk together the sifted flour, baking soda, and salt. This helps to evenly distribute the leavening agent.

Gradually add the dry ingredients to the wet mixture, folding gently with a rubber spatula. Be careful not to overmix, as this can result in a dense bread.

If using, fold in the chopped walnuts for added texture and flavor.

Pour the batter into the prepared loaf pan, smoothing the top with the spatula.

Bake in the preheated oven for 55-65 minutes, or until a toothpick inserted into the center comes out clean.

Once baked, remove from the oven and let it cool in the pan for 10 minutes before transferring to a wire rack to cool completely.