Preheat the oven to 350 degrees F. Grease and flour a 9×5 inch loaf pan.In a large mixing bowl, beat the butter and sugar until creamy. Beat in the vanilla, salt and bananas and beat until smooth.With mixer on low speed, beat in the eggs and sour cream.In a second bowl, thoroughly stir together the flour, baking powder and baking soda.
Add to the batter and stir by hand until mixed. Stir in the nuts.
Pour into the pan and bake for 55 minutes to an hour.