Preheat your oven to 180°C (350°F). Line a 15 cm x 15 cm (7 inch x 7 inch) brownie pan with parchment paper.

In a mixing bowl, mash the ripe bananas until smooth, then blend in the cocoa powder and peanut butter until you have a rich, dark chocolate batter.

Pour the brownie batter into the prepared pan and smooth it out evenly.

Bake in the preheated oven for 22 to 30 minutes. Check for doneness at 27 minutes.

Remove the brownies from the oven and cool at room temperature for about 15 minutes.

Slice the cooled brownies into squares and serve.