Preheat the oven to 180°C (356°F).
Mash the banana in a bowl.
Add almond flour, cocoa powder, and baking powder, then mix together.
Add the egg, honey, and vanilla extract, and mix well.
Pour the batter into an oven-safe pan.
Bake in the oven at 180°C (356°F) for 20 minutes.
Let it cool before serving.