To make the pastry: Cream the sugar and butter in a food processor. Add the flour, run the mixer and then add the eggs. The mixture should come together. If not, then add a tiny amount of very cold water. Scrape out, ball and wrap.

Combine all filling ingredients in a bowl

To assemble and bake: Heat an oven to 190˚C. Grease a springform cake tin with butter and line the base with a circle to baking paper. Put the tin on a baking sheet to catch any leaks during baking.

Reserve a quarter of the pastry for the lid. Using your hands, push chunks of the remaining pastry into the bottom and sides of the cake tin until it is fully and evenly lined.

Pour in the filling and press down a little.

Crumble up the remaining pastry into small pieces and dot all over the top of the pie. Then press and spread the dots to form a closed lid over the filling. Use a spatula if that helps.

Brush the pie with the beaten egg and sprinkle over with brown sugar and some more chopped walnuts. Pit the tin and its tray in the oven for 45 mins. If the pastry is getting dark at this point, loosely cover the pie with tin foil to prevent burning. Cook for a further 30 mins.

Take the pie out of the oven and stick a skewer in it. The apples should be soft. If not, return and bake another 10 mins or so.

Once done, remove the pie from the oven, discard the foiled and allow to cool in its tin for at least 3 hours. It is essential it is fully cool before it is released from its tin. Release with a small spatula and present on a flat plate.