Preheat your oven to 350°F (175°C).
In a large mixing bowl, combine the mashed bananas and honey. Stir until well mixed.
Add in the peanut butter and vanilla extract to the banana mixture. Mix until smooth.
Slowly add the cocoa powder, making sure to sift it to avoid any lumps.
Sprinkle in the baking soda and salt, then gently fold everything together until you have a smooth batter.
Pour the batter into a greased 8×8-inch (20×20 cm) baking dish, spreading it out evenly.
Pop it into the oven for about 20-25 minutes. To check for doneness, insert a toothpick into the center. If it comes out with a few moist crumbs, you’re golden.
Once done, remove from the oven and let it cool in the pan for about 10 minutes before transferring it to a wire rack.