Apple Crumble with Vanilla Custard

Ingredients

• 1 tsp ground cinnamon
• 50g caster sugar
• Pinch fine sea salt
• 800g eating apples (e.g. Braeburn), peeled, cored and thickly sliced
• 1 tbsp lemon juice, fresh
• 100g plain flour
• 75g rolled oats
• 60g demerara sugar
• 25g light brown sugar (optional, for extra caramel notes)
• 100g unsalted butter, cold and diced
• 3 egg yolks
• 1 tbsp cornflour
• 500ml whole milk
• 40g caster sugar (for custard)
• 1 tsp vanilla extract (or seeds of ½ vanilla pod)

Method

1. Heat the oven to 190°C fan. Tip the sliced apples into a large bowl with the caster sugar, lemon juice, cinnamon and a proper pinch of salt — don't skip the salt, it's what makes the cinnamon and apple taste of themselves rather than just sweet. Toss until every slice glistens.
2. Spread the apples into a shallow ovenproof dish (around 1.5 litres) in a single even layer so they soften but hold their shape rather than collapsing into mush.
3. Rub the cold diced butter into the flour with your fingertips for 2–3 minutes until the mixture looks like coarse, uneven crumbs. Keep some pea-sized lumps — that's what gives you the craggy texture. Stir through the oats, demerara and light brown sugar, then taste a pinch of the raw crumble: it should taste faintly savoury under the sweetness. If it's flat, add another small pinch of salt to lift the caramel notes.
4. Scatter the crumble over the apples in a thick, generous layer — don't press it down, you want air pockets for crunch. Bake for 35–40 minutes until the topping is deeply golden and the juices are bubbling thickly at the edges. Pale crumble means underbaked crumble; wait for proper colour.
5. While it bakes, warm the milk and vanilla in a saucepan over a low heat until just steaming — don't let it boil or you'll catch the milk and the custard will taste scorched. In a bowl, whisk the egg yolks, caster sugar and cornflour to a pale, smooth paste.
6. Pour a ladleful of hot milk into the yolks, whisking constantly to temper them — straight in and you'll scramble the eggs. Tip the lot back into the pan and stir continuously over a low heat for 3–4 minutes until the custard coats the back of a spoon and a finger drawn through leaves a clean line. Pull it the moment it thickens; it carries on setting off the heat.
7. Rest the crumble for 5 minutes so the filling settles and the juices stop volcano-ing. Spoon the crumble into bowls while the topping is still crackling and the apples are steaming, then pour the warm custard over each portion at the table — pouring cream alongside for anyone who wants both.