Preheat the oven to 180 degrees C (350 degrees F).
Sift the flour, baking soda and salt into a large mixing bowl.
In a separate bowl, cream the butter and sugar together until light and fluffy.
Add the eggs, mashed bananas, buttermilk and vanilla extract to the butter and sugar mixture and mix well. Fold in the flour mixture. Optional, add the pecans, or chocolate chips or walnuts.
Grease a 8in x 5in loaf tin and pour the cake mixture into the tin.
Transfer to the oven and bake for about an hour, or until well-risen and golden-brown.
Remove from the oven and cool in the tin for a few minutes, then turn out onto a wire rack to cool completely before serving.