Preheat your oven to 350°F (175°C).
In a large bowl, combine sliced apples, granulated sugar, lemon juice, cinnamon, nutmeg, and cornstarch. Mix well.
Pour the apple mixture into the pie crust, spreading evenly.
In another bowl, mix flour, brown sugar, and salt for the crumble topping.
Add cold butter to the dry ingredients and mix until crumbly.
Sprinkle the crumble topping over the apple filling.
Bake in the preheated oven for 45 minutes or until the topping is golden brown.
Remove from the oven and let cool for at least 10 minutes.
Serve warm with vanilla ice cream or whipped cream.
Enjoy your homemade apple crumble pie!