Preheat oven to 350 degrees Fahrenheit (175 degrees Celsius).

In a large bowl, combine sour cream, sugar, softened butter, and eggs.

Mix on low speed for 1 minute until well combined.

Add mashed bananas and vanilla extract to the mixture.

Mix on low speed for another 30 seconds.

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

Gradually add the dry ingredients to the wet ingredients.

Mix on medium speed for 1 minute until just combined.

Gently fold in the minced nuts.

Spread the batter evenly into a 15 1/2 x 10 1/2 x 1 inch baking pan.

Bake for 20-25 minutes, or until a toothpick inserted into the center comes out clean.

Allow the bars to cool completely before frosting and serving.