Add pork, cider and chicken stock to a slow cooker and cook on low over night.
Next morning, heat fry pan with a good glug of olive oil and add onion. Cook well until golden brown then add carrot and potato. Cook until carrot is soft.
Meanwhile, take the pork out of the stock and pull the meat apart on a large plate and add to the onion mixture. In a small cup add cornflour and 1/2 cup of the stock and mix well. Add to the fry pan along with the Worcestershire sauce and rosemary. Cook for another 10 minutes on medium heat, then remove from heat to let cool completely.
Next to make the pastry add flour, salt and butter to a food processor and blitz until it resembles bread crumbs. Add milk and chilled water. If the mixture is still dry and not quite coming together add more water until it can all be brought together in a ball.
Flour surface and roll out pastry and cut into circles 18cm in diameter and 3mm thick. I used a small plate to carefully cut around. Repeat with the remaining pastry.
Once all the pastry has been rolled out and the filling is cool enough, spoon filling into the centre of each pastry. Brush the edges with beaten egg and gently bring the edges together. Crimp the edge (this will help keep it all together) and brush pastry with remaining egg wash. Cut a small slit at the top of each pasty and repeat with the remaining mixture. Place all completed pasties in the fridge for 30 minutes.
Preheat oven to 200°C. Place pasties on a lined baking tray and bake for 20 minutes. Turn the oven down to 160°C and cook for a further 20-30 minutes or until golden brown. Serve with corn relish, homemade chutney or any good quality tomato sauce.