In a mixing bowl, combine the flour, sugar, baking powder, cinnamon, butter, and salt. Mix until the ingredients form a cohesive dough. Transfer to the freezer while preparing the apples.
Peel the apples and cut them into bite-sized cubes. Place them in a large bowl and toss with sugar, cinnamon, cornstarch, lemon juice, and vanilla extract. Stir well to coat the apples evenly.
Preheat the oven to 355°F (180°C).
Grease a 9.5-inch/24 cm baking dish with butter. Spread the apple mixture evenly in the dish. Remove the crumble from the freezer and break it into small pieces over the apples. If too firm, let it sit at room temperature for 10 minutes before crumbling by hand or grating with a box grater.
Bake for 40 to 50 minutes, until the topping is deeply golden and the apples are bubbling. Let cool for a few minutes before serving warm with ice cream.