Lightly oil a well seasoned 10" cast iron skillet.
Peel and core the apples and cut into slices. Mix the apples, cinnamon and sugars in a large bowl and set aside.
Put the milk, and eggs into a blender or food process and mix well. Add the flour, nutmeg and salt and process until smooth.
Melt the butter in the prepared skillet over medium heat. Add the apple mixture and cook, stirring gently until all the sugars have melted and the apple slices are nicely coated. About 5 minutes.
Pour the batter over the apples. Bake until the edges are puffed and golden and the apples are tender, about 20 to 30 minutes. Serve immediately