Preheat oven to 375 F.
Spray an 8x8 inch square baking dish with oil or cooking spray.
In a medium bowl, mix together the oats, baking powder, cinnamon, ginger, nutmeg and salt.
In another bowl, whisk together the almond milk, mashed banana, maple syrup, molasses, egg, and vanilla.
Add the dry ingredients to the wet ingredients and stir to combine, making sure everything is well mixed.
Stir in the diced apple and chocolate chips.
Transfer oatmeal mixture into the prepared baking dish.
Add apple slices on top.
Bake for 30 minutes, until the top is golden and center is set.
Remove from the oven and let cool for a few minutes.