Preheat your oven to 350°F (175°C) and grease a 9-inch loaf pan with butter or cooking spray, dusting it lightly with flour.

In a large mixing bowl, cream together ½ cup of softened unsalted butter and 1 cup of granulated sugar until light and fluffy, about 3-5 minutes.

Incorporate 2 large beaten eggs, mixing well after each addition for a rich, creamy consistency.

In a separate bowl, whisk together 1 ½ cups of all-purpose flour, 1 teaspoon of baking soda, and ½ teaspoon of kosher salt.

Gradually add the dry ingredients to the butter and egg mixture, stirring gently until just combined.

Fold in 1 cup of mashed very ripe bananas, ½ cup of sour cream, and 1 teaspoon of pure vanilla extract until evenly distributed.

Pour the batter into the prepared loaf pan, filling it about ¾ full, and level the top with a spatula.

Bake in the preheated oven for 50-55 minutes, or until a toothpick inserted into the center comes out clean.

Allow the bread to cool in the pan for about 10 minutes, then transfer to a wire rack to cool completely before slicing.