Cut the bananas into round slices into a deep container. Mash well. Then add the brown sugar to them. Mash again until homogeneous. Then add the cinnamon, baking soda, baking powder and oil. Mash or stir well.
Then gradually begin adding the flour while stirring nonstop. Stir until you obtain a homogeneous mixture.
Then smear a cake form with oil and flour it. Pour the cake mixture into it.
Bake the cake in a preheated 374°F (190 °C) oven for about 25-30 min. Once the cake is ready, take it out of the oven, leave to cool, take out of the form.