Preheat your oven to 375°F (190°C) and line a 9-inch pie dish with your pie crust. If you’re using store-bought pie crust, fit it into the dish and crimp the edges.
2. Prepare the Apple Filling:
In a large bowl, combine the sliced apples, granulated sugar, brown sugar, flour, cinnamon, nutmeg (if using), lemon juice, and vanilla extract. Toss to coat the apples evenly in the sugar and spice mixture.
Pour the apple filling into the prepared pie crust, spreading it out evenly.
3. Make the Cinnamon Crumble Topping:
In a medium bowl, combine the flour, oats, brown sugar, cinnamon, and salt.
Add the cold, cubed butter. Use a pastry cutter, fork, or your hands to work the butter into the dry ingredients until the mixture resembles coarse crumbs. Be sure the butter remains in small pea-sized pieces.
Sprinkle the crumble topping evenly over the apple filling.
4. Bake the Pie:
Place the pie on a baking sheet (to catch any drips) and bake for about 45-50 minutes, or until the apples are tender and the topping is golden brown and bubbly. You may need to cover the edges of the pie crust with aluminum foil during the last 10-15 minutes of baking to prevent over-browning.
5. Cool and Serve:
Once the pie is done, remove it from the oven and let it cool for at least 2 hours to allow the filling to set.
Serve the pie warm or at room temperature, optionally topped with a scoop of vanilla ice cream or a dollop of whipped cream.
