Preheat your oven to 350°F (175°C) and grease a 9-inch loaf pan with butter and flour.

In a mixing bowl, combine softened butter and sugar; beat on medium speed for 3-5 minutes until light and fluffy.

Add the beaten eggs and mix on low speed until fully incorporated (about 1-2 minutes).

In a separate bowl, whisk together flour, baking soda, and salt. Gradually add to wet ingredients on low speed to combine.

Fold in the mashed bananas, sour cream, and vanilla extract using a spatula until blended.

Transfer the batter to the prepared loaf pan, filling about ¾ full. Bake for 50-55 minutes.

Remove from oven and let cool in the pan for 10 minutes before transferring to a cooling rack.