Preheat your oven to 375°F/190°C and lightly grease your baking pan or skillet.
Cut the apples in half, scoop out the seeds with a spoon, and cut out what's left of the core with a knife. Then arrange the apples in the bottom of your greased baking pan.
In a small bowl, mix together the oats, oat flour, brown sugar, coconut oil or melted butter, ground cinnamon, and salt.
Evenly distribute the topping over each halved apple, lightly pushing it down (some will fall down into the skillet/pan).
Cover with foil, a lid, or a baking sheet and bake for 25 minutes, remove the cover and bake for another 20 minutes until the apples are soft and the oatmeal topping is lightly golden brown.
Enjoy as is or top with vanilla ice cream.