Instructions:
- Preheat your oven to 375°F (190°C).
- In a large mixing bowl, combine the sliced apples, granulated sugar, flour, cinnamon, nutmeg, and salt. Mix until the apples are evenly coated with the dry ingredients.
- Transfer the apple mixture to a 9x9-inch baking dish and dot the top with the butter pieces.
- In a separate bowl, combine the rolled oats, brown sugar, flour, cinnamon, nutmeg, and salt. Mix until well combined.
- Add the cold butter to the oat mixture and use your fingers or a pastry blender to work the butter into the dry ingredients until the mixture resembles coarse crumbs.
- Spread the crumble topping evenly over the apple filling, making sure to cover the entire surface.
- Bake the apple crumbler for 40-45 minutes, or until the topping is golden brown and the apples are tender.
- Remove the dish from the oven and let it cool for a few minutes before serving. Serve warm, topped with vanilla ice cream or whipped cream if desired.