Preheat the oven to 180ºC. Line a 20x20cm baking tray with baking paper.

Take a bowl and mash the bananas with a fork. Add the oats (in flakes or ground into oat flour), the nut butter of your choice and rougly chopped chocolate pieces.

Pour the dough in the tray and bake for 18-20 mins, or until a toothpick comes out clean.

Let it cool down and once at room temperature, slice into individual servings.