Melt 30g of butter in a large frying pan over medium heat, add 500g of Bramley apples and 300g of Russet apples, sprinkle with 100g of caster sugar, and cook for 10 to 15 minutes until tender.

Remove the pan from heat, add the finely grated zest of one lemon, and stir to combine.

In a separate saucepan, warm 600ml of milk over low heat. Beat four egg yolks in a mixing bowl, gradually whisk in the warm milk. In another saucepan, melt 50g of butter, stir in 40g of flour or cornflour, and pour in the milk mixture, whisking until thickened.

Spread the apple mixture in a greased baking dish, pour the custard over the apples, and mix 50g of demerara sugar with ground cinnamon to sprinkle on top.

Preheat the grill to medium-high, place the pudding under the grill for 5 minutes until the sugar caramelizes.

Let the pudding cool for about 15 minutes before serving.