Add the flour, sugar, baking powder, and salt to a bowl and mix.

Then add the liquid ingredients (except the egg), the bananas that have been mashed, and once mixed, add the egg and mix well until combined.

The mixture should be slightly thick but pourable.

If it's too thick, add milk; if it's too runny, add flour.

Grease your baking dish and place it in a preheated oven at 350°F (180°C) for one hour, then switch to convection for another 30 minutes.