Mash the banana in a bowl with a fork. Add the egg, oatmeal and flour and whisk. Add enough milk until the batter has the consistency of a pancake batter. Peel the apple, remove the core, cut the pulp into very fine cubes and stir them into the batter. Add salt, sugar and baking powder and stir. Preheat a pan. Fry the batter in the preheated pan in butter or oil until the pancakes are golden brown on both sides.