Preheat oven to 350.
Place butter in baking dish (9x13) and place in oven until melted. Remove from oven and set aside.
Core, peel and slice apples and place in large bowl.
Add 1/4 cup flour, brown sugar, cinnamon and nutmeg to apples. Mix until well coated.
In another large bowl, whisk together remaining flour, sugar, baking powder and salt until blended.
Pour in milk slowly while whisking
Pour batter into baking dish over melted butter.
Pour apple mixture over batter.
Bake 45-50 minutes until golden brown.