Grease the base and sides of a 9inch (23cm) pie dish with butter.
Make the shortcrust pastry. Place the flour, butter and trex into a large bowl. Incorporate all the butter using the rub in method with your fingertips. Tip: Using a food processor will make the job quicker and easier.
350 g White Spelt Flour or Plain White Flour, 100 g fridge cold butter, 75 g Trex
Add just enough of the water and bring the mixture together until you have a ball of dough with a smooth, putty like texture. Do not over handle the dough or you will stretch the gluten and the pastry will become tough.
5 - 6 tablespoons of very cold water
Wrap the pastry in baking parchment or cling film, flatten it a little and place the dough in the fridge for at least 30 mins to rest.
While the pastry is resting, place a large baking tray in the oven and preheat to 200c deg (fan assisted oven)
Core the apples and slice them thinly about ¼ inch thick. There’s no need to peel them if you don’t want to. Apple skins are a great source of fibre for gut health. Toss the slices of apples with the lemon juice in a large bowl.
850 grams Apples, Juice about half a lemon
Mix together the Sugar, Corn Flour and Cinnamon if using, then add to the slices of Apple and give everything a good mix taking care not to break up the fruit.
3 level tablespoons Corn Flour, 75 g Soft Brown Sugar, ½ teaspoon ground cinnamon
If adding frozen or fresh berries do so at this stage, and gently mix them with the apples.
200 g frozen or fresh berries such as strawberries and blueberries
Remove the pastry from the fridge and cut off just over half the amount. Leave the rest in the fridge.
Roll out the pastry into a circle, on a lightly dusted surface, until it measures about 14 inch (36cm). Rolling between two large sheets of baking parchment will make the job easier and eliminates the need for extra flour. Carefully line the baking dish with pastry.
Add the Apple and Berry filling and brush the pastry edges with a little milk.
Roll out the remaining pastry from the fridge, until it is large enough to cover the top of the Apple Pie. Brush the edge of the pastry lining the baking dish, with milk, place the pastry lid over the top of the apples and press firmly around the edges to seal. Crimp the pie edges with a fork or your fingers, and make a small hole in the centre to release the steam during baking.
Roll out and cut any remaining pastry trimmings into leaf shapes and arrange them in a circle around the opening. Brush the pastry top and leaves with milk and scatter with a little caster sugar.
Place the pie on the preheated baking tray and bake for 15 mins. Then reduce the temperature to 160c deg and bake for a further 35 mins or until baked and the pie has a golden colour.