Preheat the oven to 375 degrees. Butter an 8x8 pan and set aside.
Wash and dry the apples. Remove the core and if desired, peel the apples. You can also leave the peels on the apples. Thinly slice the apple into ¼-inch slices.
Place the apples into the buttered baking dish. The baking dish should be about three-quarters of the way full.
Combine the oats, sugar, nutmeg, cinnamon, and flour in a medium mixing bowl. Add in the butter, and with a pastry cutter or your hands, combine the mixture until crumbly and the butter is evenly distributed through the mixture. Sprinkle evenly over the apples.
Cover with foil and bake for 20 minutes. Remove the foil, and continue to bake for an additional 15-20 minutes, or until apples are tender and topping is golden brown.
Serve warm with whipped cream. milk, or vanilla ice cream.
Apples--The best apples for apple crisp are Granny Smith, McIntosh, or Gala apples, you can even use a variety of apples. Oats--Use either old-fashioned rolled oats or quick-cooking oats for this apple crisp. Do NOT steel-cut oats!Flour--All-purpose, whole wheat, white wheat all work for this recipe. Even a 1:1 Gluten-Free Flour mix works to make this gluten-free apple crisp.Storage: Apple crisp can be stored, covered, for 3-4 days in the refrigerator. Doubling: This recipe can easily be doubled, simply use a 9x13 pan or a 4-quart baking dish.