Step 1: Preheat your oven to 375°F (190°C). Lightly grease an 8x8 inch or 9-inch round baking dish.nStep 2: In a large bowl, combine the sliced apples, 1/2 cup granulated sugar, 1 tablespoon flour, 1 teaspoon cinnamon, and nutmeg (if using). Toss gently until the apples are evenly coated. Pour the apple mixture into the prepared baking dish and spread evenly.nStep 3: In a separate medium bowl, whisk together the 1 cup flour, rolled oats, brown sugar, 1/4 cup granulated sugar, and 1/2 teaspoon cinnamon (if using).nStep 4: Add the cold, cubed butter to the dry topping ingredients. Using your fingertips or a pastry blender, cut the butter into the mixture until it resembles coarse crumbs with some pea-sized pieces of butter remaining.nStep 5: Sprinkle the crumble topping evenly over the apple mixture in the baking dish.nStep 6: Bake for 40-45 minutes, or until the topping is golden brown and the apple filling is bubbling around the edges and tender when pierced with a knife.nStep 7: Let the apple crumble cool for at least 15 minutes before serving to allow the filling to set slightly. Serve warm with your favorite accompaniments.