Mash the bananas with a fork.
In a bowl, combine the mashed bananas, sugar, egg, and melted butter.
Sift in the flour, baking powder, and salt, then mix together.
Pour the batter into a pound cake mold lined with parchment paper.
Bake in a preheated oven at 180°C (356°F) for 35–40 minutes.
Remove from the pan and let cool on a wire rack.