Preheat the oven to 180°C hot air (top/bottom heat: 200°C). Grease a box mould and place in the refrigerator.
Peel and crush the 3 ripe bananas. Now stir the butter with the sugar until foamy, then mix in the eggs and the crushed bananas. Mix the flour with the baking soda and fold in. Finally add the chopped nuts.
Fill the dough into the box form.
Put in the hot oven and bake for 3/4 to 1 hour - try cooking.
If you like, you can cover the banana bread with melted chocolate coating.