Preheat the oven to 175 oC

With a wooden spoon, mix butter into the mashed bananas in a large bowl.

Mix in the sugar, egg and vanilla.

Sprinkle the baking soda and salt over the mixture and mix in

Add the flour last, mix.

Pour mixture into buttered loaf pan

Bake for 1 hour

Cool on a rack. Remove from pan and slice to serve