Prepare all ingredients. Mash banana. Lightly beat eggs. Break chocolate bars.
Preheat the oven to 160 degrees Celsius (depending on the oven) Line a 9-inch square baking tin with baking paper, with an extra few cm on the sides.
Combine butter, sugar and chocolate in a large pan and gently cook over a gentle flame, keep stirring until melted and smooth. Remove pan from heat.
Stir in the combined eggs, bananas and vanilla until well-mixed.
Sift in the flour and cocoa powder by folding in the mixture until JUST mixed. Pour the mixture into the prepared tin and bake for 35 minutes at 160 C. Allow brownie to cool. Decorate as desired. Nutella is used here as kids love it so much.
