Ingredients
Filling
5 to 6 tart apples, such as Granny Smith, peeled, cored, and cut into 3/4-inch-thick slices (if you use sweet apples instead, squeeze in approx. 1/2 t. of lemon juice to cut down the sweetness)
2 T. granulated sugar
2 T. lightly packed brown sugar
1 1/2 t. cinnamon
1/4 t. nutmeg
2 T. unsalted butter, melted
Topping
3/4 cup plus 2 T. all-purpose flour
1/4 cup plus 2 T. old-fashioned oatmeal
1/4 cup plus 3 T. granulated sugar
1/4 cup plus 3 T. lightly packed brown sugar
12 T. unsalted butter, cut into small pieces and slightly softened