Preheat your oven to 350°F (175°C). Grease and flour a loaf pan.

In a large bowl, mash the overripe bananas until smooth.

In another bowl, cream together the butter and sugar until light and fluffy.

Beat in the eggs one at a time, then stir in the vanilla extract.

Add the mashed bananas and sour cream to the butter mixture and mix well.

In a separate bowl, whisk together the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Pour the batter into the prepared loaf pan and bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.

Let the bread cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.