Preheat the oven to 175 degrees Celcius.
Lina a baking pan with parchment paper.
Combine the flax egg while you prepare the rest of the ingredients (if using flax egg).
Mash the banana in a bowl.
Add vanilla drops and egg/flax egg to the banana and combine.
Add oats, oat flour, baking powder, cinnamon and salt to the bowl and mix well.
Add half of the batter to the baking pan and spread to an even layer.
Sprinkle berries on the oat mixture evenly.
Add rest of the oat mixture on top.
Bake in the oven for 25-30 minutes, until golden brown.
Let it cool before cutting.