Preheat your oven to 350°F and lightly grease an 8x8-inch baking dish.

In a large mixing bowl, combine the diced Granny Smith apples, chopped dates, brown sugar, lemon juice, cinnamon, nutmeg, cornstarch, and vanilla extract. Stir until evenly combined.

Transfer the apple mixture to the prepared baking dish and spread into an even layer.

In a separate bowl, combine the flour, old-fashioned oats, brown sugar, cinnamon, and salt.

Add the cold, cubed butter and use a pastry cutter or fork to work it into the dry ingredients until coarse crumbs form.

Sprinkle the crumble topping evenly over the apple filling.

Bake for 35–40 minutes, or until the topping is golden brown, the filling is bubbling, and the apples are tender.

Remove from the oven and let cool for approximately 10 minutes.

Serve warm with vanilla ice cream or caramel sauce, if desired, and enjoy!