Preheat your oven to 350°F (175°C). Grease a 9x9-inch baking dish.

In a large bowl, combine the diced apples, granulated sugar, lemon juice, flour, salt, and cinnamon. Toss until the apples are evenly coated. Pour the apple mixture into the prepared baking dish and spread it out evenly.

In another bowl, whisk together the flour, brown sugar, baking powder, salt, and cinnamon for the crumble topping.

Add the cold, cubed butter to the dry ingredients. Use a pastry cutter or your fingers to work the butter into the mixture until it resembles coarse crumbs.

Evenly sprinkle the crumble topping over the apple mixture, ensuring the apples are fully covered.

Bake in the preheated oven for 35-40 minutes, or until the topping is golden brown and the apple filling is bubbling around the edges.

Remove the dish from the oven and let it cool for about 5-10 minutes.

Serve the apple crumble while still warm. Best served with a scoop of vanilla ice cream, and a drizzle of caramel sauce. Enjoy!