Using a mixer, cream together butter and sugar. Add eggs, mashed bananas, buttermilk and vanilla. Mix well.
Add in the flour, baking powder, salt and baking soda. Mix until well combined. Pour into loaf pan.
Bake for 50-55 minutes or until a toothpick comes out clean.
Let the bread cool on a wire rack for 15 minutes. Then using a knife, run it around the edge of the pan and carefully remove from the pan. Let cool completely.
Recipe by Crumbs and Chaos at http://www.crumbsandchaos.dreamhosters.com/2015/05/the-best-buttermilk-banana-bread/