Preheat oven to 180°C fan / 200°C conventional. Lightly grease a 12-hole mini loaf tin with butter.
In a large mixing bowl, cream the butter and caster sugar until light and fluffy.
180 grams Unsalted butter or margarine (I use Stork), 150 grams Golden caster sugar
Beat in the eggs, one at a time, until well combined. You can add 1 tbsp of the 240g flour with each egg to stop the mixture from curdling.
2 large Eggs
Add the flour and gently fold the mixture until smooth and just combined.
240 grams Self-raising flour
In a separate bowl, mash the bananas until smooth and puréed. Then fold into the sponge mixture.
2 medium Ripe bananas