Preheat oven to 350 degrees F.
In a small bowl, combine oats, flour, sugar and spices. Pour melted butter overtop and stir to combine.
Cut apples in half and remove core. Place each half in a small oven proof casserole dish.
Spoon mixture on top of each apple half. Feel free to dust with a little extra cinnamon and freshly grated nutmeg.
Place in preheated oven for about 30 minutes, or until apples have cooked through and softened.
Best served warm with a small serving of vanilla ice-cream, if desired.