Put the butter into a medium-sized pan and let it melt.

Peel and core the cooking apples then slice roughly and put in the saucepan.

Peel, core and chop the eating apples into small chunks. Add to the pan.

Tip the sugar in and cook everything over medium heat, stirring often, until the cooking apples break down and the eating apples feel fork tender (around 10-15 minutes).

Optional step: if there is alot of watery liquid in the bottom of the pan once the apple are cooked drain it away.

Finely grate the lemon, toss the zest into the pan and stir through. Set aside.

Beat the egg yolks into the milk.

Melt the butter in a small pan (not a milk pan).

Toss in the flour, mix with a wooden spoon until smooth and cook for 1 minute.

Take the pan off of the heat and add the milk, little by little, stirring until smooth each time.

Tip the sugar in.

Put the pan over moderate heat and cook, stirring constantly, until the custard thickens nicely.

Stir the vanilla extract/ vanilla bean paste through.

Tip the apple mixture into the base of the baking dish and spread out.

Pour the custard over the top and level it out if necessary.

Mix the cinnamon and demerara sugar together then sprinkle over the top of the custard, ensuring that the entire top is covered evenly. Keep on sprinkling to use up all of the sugar.

Place the bowl under a pre-heated grill (2-3 cm below it) and cook for around 5 minutes until the sugar has melted and is bubbling in places (alternatively use a kitchen blowtorch to achieve this). Turn the dish as necessary to ensure an even bake.

Remove the pan from the oven and set aside for 15 minutes for the sugar to cool and firm up. Serve the pudding whilst it is still warm.