Preheat your oven to 350°F (175°C). Grease a baking pan.
In a mixing bowl, whisk together the flour, baking powder, baking soda, and salt.
In another bowl, mix the mashed bananas, Nutella, melted butter, sugar, eggs, and vanilla extract until well combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the batter into the prepared baking pan and spread it evenly.
Bake for 45 minutes or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.