Preheat your oven to 180°C (350°F).
Peel and core all the apples carefully.
Cut them into thin slices.
Place apple slices in your saucepan.
Add sugar, cinnamon, and water to apples.
Cook on medium heat for 5 minutes.
Stir occasionally until apples soften slightly.
Transfer the mixture to your baking dish.
Put flour into your large mixing bowl.
Add the cold butter cubes to flour.
Rub butter into flour with your fingertips.
Keep rubbing until it looks like breadcrumbs.
This takes about 3 minutes of rubbing.
Mix in both sugars until evenly combined.
Sprinkle the crumble mixture over the apples.
Spread it evenly across the entire surface.
Don't press down on the crumble topping.
Place the dish in your preheated oven.
Bake for 35-40 minutes until golden brown.
The topping should look crispy and beautiful.
Let it cool for 5 minutes before serving.