Preheat the oven to 200 degrees top / bottom heat.
Beat the butter, sugar and eggs until frothy. Mash the bananas, stir in. Mix the flour and baking powder and stir into the mixture.
Grease a small baking sheet (approx. 30 x 22 cm) and spread the dough on it. Bake until golden brown for approx. 15 - 20 minutes. Make a trial! Every oven bakes differently.