In a mixing bowl beat butter and sugar. When light and fluffy add vanilla and slowly beat in eggs and yoghurt. Then fold in by hand the mashed bananas.
Fold in by hand the sifted flour with nuts, mixing until combined.
Preheat the oven to 175-180*C. Spray oil and line a slice tray (28x18cm).
Bake for about 45 mins depends on your oven. Test with a skewer. Take out of oven and cool in the tin on a wire rack. If you wish to ice you can do this now while still warm or put on a cream cheese icing when properly cooled. Cut into squares or slices to serve.
I freeze this and it defrosts nicely on the bench.
The original recipe had sour cream I don't really use sour cream so subbed in the yoghurt, this works so well and it made a nice moist banana cake.