Set the oven to 180°C / 350°F with the fan.
In a bowl, mix all the dough ingredients well.
Divide the dough batter to 2, one half should be flattened on a greased pan (9x13).
Bake for 15 minutes.
In a bowl, mix well the filling ingredients.
On the half-baked bottom dough, pour the filling on top.
Crumble with your hands the other half of the dough and sprinkle on top of the filling.
Bake for 40 minutes.
Cool at room temperature.
Cut into bars.
Have an apple bar, or three, and enjoy!