Preheat your oven to 425°F (220°C). Line a 9-inch pie dish with parchment paper and fit the pie crust snugly.

In a large bowl, toss sliced apples with sugar, lemon juice, cinnamon, and nutmeg. Let sit for 10 minutes to macerate.

Arrange the apple slices evenly in the prepared crust. Drizzle any leftover juices over the top for extra sweetness.

In another bowl, combine flour, brown sugar, oats, salt, and cubed butter. Use a pastry cutter or fingers to blend until coarse crumbs form.

Sprinkle the crumble evenly over the apples. Place on a baking sheet and bake for 15 minutes at 425°F, then reduce heat to 350°F (175°C) and bake 40–45 minutes more until topping is golden and filling bubbles.

Let the pie rest on a wire rack for at least 1 hour to set. This helps achieve clean slices and a crisp crust.

Serve warm or at room temperature with a scoop of vanilla ice cream or a dollop of whipped cream.