Preheat the oven to 200C/400F/gas 6.
Grease the tart tin with butter.
To make the pastry sift the flour and salt into the mixing bowl or food processor bowl.
Add the butter and then rub it in (or process if using food processor) until the mixture resembles fine breadcrumbs.
Place the egg yolk into a cup and add the ice cold water and whisk together.
Add to the pastry mix and bring together to make a dough adding more water if the dough is too dry. If using a processor add the egg mixture and whizz until the mixture forms a ball of dough.
Wrap the dough in clingfilm and place in the fridge for 30 minutes.
While the pastry is chilling, score the apples around the middle and place in a roasting tray and bake in the oven until the flesh is soft (about 20 minutes).
Remove from the oven and scoop out the apple flesh and place in the small bowl.
Reduce the oven temperature to 180/350F/gas 4.
Take the pastry out of the fridge and roll out on a lightly floured work surface and line the tart tin with it.
Prick the bottom with a fork and place in the fridge for half an hour.
Take the lined tart tin out of the fridge.
Scrunch up a large piece of baking paper, open it out and place over the pastry. Fill with baking beans and bake in the preheated oven for 15 minutes.
Take out of the oven, remove the paper and baking beans and brush the pastry with the beaten egg. Return to the oven for a further 10 minutes. Set aside to cool.
To make the filling, place the egg and egg yolks in a mixing bowl, add the caster sugar and whisk together until pale and creamy. This will take about 5 minutes.
Add the chopped apple, lemon zest and clarified butter and whisk until fully incorporated.
Stir in the breadcrumbs and mixed peel.
Pour the mixture into the prepared pastry shell and bake for 30-40 minutes or until the filling is set and the top golden.
Take out of the fridge and allow to cool a little before removing the tart tin and transferring the ‘pudding’ to a serving dish.
