grease a 23cm square slab pan, cover base with paper and grease paper
sift flour and soda into a bowl
make a well in centre of flour mixture
stir in sugar, eggs, banana and oil, and mix to a smooth batter
pour mixture into prepared pan
bake in oven for 1 ½ hours, or until cooked when tested
let cake stand in pan for 10 minutes, turn onto wire rack to cool
spread icing over cooled cake