Preheat your oven at 180℃ (355℉).
Mash your banana(s) in a large bowl.
In a liquid measuring cup, add the milk, the vanilla and the eggs (if using). Mix well and add the mashed banana. Mix again.
In the big bowl mix the oats, cinnamon, nutmeg, cloves, allspice, baking powder and salt.
Pour the wet mixture over the dry and mix just until everything is combined.
Add 1 1/2 cups of the chopped apples and carefully fold them in.
Spray your 9x9 baking dish with cooking spray and pour your batter into it. Spread the rest of the chopped apples on top and cover with aluminum foil.
Bake at 180℃ (355℉) covered with aluminum foil for 20 min, then remove the foil and bake for an additional 10-15 minutes.