Place in a large bowl the oats along with the flour, baking powder, cinnamon and salt and mix well.
Add the mashed bananas along with the maple syrup and mix well.
Drop in the raisins and mix well.
In the meantime, turn on the oven to 175°C, air circulation and rack set at the middle
Use a small baking dish, about 9x9 inches and brush all over the oil. Add the mixture and with the use of a spatula spread it evenly. Bake in the oven for about 25’ and until a light golden colour is achieved and darker brown colour around the edges. Remove from the oven and allow to cool, then cut in squares and refrigerate.