Preheat the oven to 180°C. Grease and line a shallow, about 20x30 cm, baking dish.
Using a fork, mash the bananas, then mix in the vanilla essence, cinnamon, ginger and oil.
Add the oats, then combine well.
Add the grated apple and mix well. Fold in the raisins, if used.
Transfer the mixture to the prepared dish, spreading it out evenly.
Bake for 20-25 minutes until golden.
Take the tin out of the oven and let it cool for a few minutes, then transfer the cake to a wire rack.
When it’s completely cool, cut it into squares or bars.