The rubbing-in method — working cold fat into flour until it resembles breadcrumbs — is one of the most important techniques in baking. It appears in pastry and other desserts, so learning it here builds transferable skill.
Preheat the oven to 180°C (fan 160°C).
Peel, core and chop 1 kg apples into chunks.
Place into a saucepan with 50 g sugar and cook over medium heat for 5–10 minutes until starting to soften.
Transfer the apples to an ovenproof dish.
In a bowl, rub 100 g butter into 150 g flour using your fingertips until it resembles breadcrumbs.
Stir in the remaining 50 g sugar.
Scatter the crumble evenly over the apples.
Bake for 30–35 minutes until golden and bubbling.