Peel and slice the apples into thin slices about ⅛ - ¼ inch thick.
Whisk together the melted butter, flour, water, sugar, cinnamon & nutmeg.
Pour the mixture over the sliced apples and toss to coat.
Spoon the apples into the greased pan.
In a medium bowl stir together the flour, brown sugar, oats, cinnamon & salt.
Add in the butter and rub it in using a pastry cutter or rub the butter into the dry ingredients using your fingers. At the end it should be crumbly in texture, but no large chunks of butter should remain. Add this crumble mixture overtop the apple mixture.
Bake in the preheated oven for 25-30 minutes, or until the top is golden brown and you can see the apples bubbling around the edges of the pan.
Remove from the oven and cool for at least 10 minutes before serving.
Serve with Custard, Cream or vanilla Ice-cream.
Recipe by at https://laurasglutenfreekitchen.com/2020/10/gluten-free-apple-crumble/