Preheat oven to 350°F (175°C). Grease a 9x5 inch loaf pan.
In a large bowl, whisk together the bananas, sugar, oil, eggs, and vanilla extract.
In another bowl, combine the flour, baking powder, salt, and soda. Fold the flour mixture into the banana mixture until just combined. Stir in the walnuts. Pour the batter into the loaf pan and bake for about 1 hour 10 minutes, until a toothpick inserted into the center comes out clean. When done, let cool for 10 minutes before taking the bread out of the pan.
The frosting:
Beat the cream cheese and butter together for 2-3 minutes, until soft and creamy. Add the powdered sugar and beat until combined. Add the vanilla and beat for 1 minute more. Add more powdered sugar until you reach your desired thickness. Add the salt.
Spread the frosting on the cooled bread. Sprinkle with some chopped walnuts. Enjoy!