1/2 cup unsalted butter, very cold
3 cups plain flour
1 tsp salt
1 Tbs sugar
1/3 cup vegetable shortening, very cold
1/2 cup Tbs ice water
2kg Granny Smith apples peeled, cored, and quartered
1 lemon, zested
1 orange, zested
2 Tbs freshly squeezed lemon juice
1 Tbs freshly squeezed orange juice
1/2 cup sugar
1/4 cup plain flour
1 tsp salt
3/4 tsp ground cinnamon
1/2 tsp ground nutmeg
1/8 tsp ground allspice
1 egg beaten with 1 Tbs water - for egg wash
Place the flour, salt and sugar in the bowl of a food processor and mix. Add the butter and shortening. Pulse 8 to 12 times, until the butter is the size of peas.
With the machine running, pour the ice water down the feed tube and pulse machine until the dough begins to form a ball. Dump out on a floured board and roll into a ball. Wrap in plastic wrap and refrigerate for 30 minutes.
Cut the dough in half. Roll each piece on a well-floured board into a circle, rolling from the center to the edge, turning and flouring the dough to make sure it doesn't stick to the board. Fold the dough in half, place in a pie pan and unfold to fit the pan. Repeat with the top crust after filling has been placed in.
Pre-heat the oven to 200 C.
Cut each apple quarter in thirds crosswise and combine in a bowl with zests, juices, sugar, flour, salt, cinnamon, nutmeg, and allspice.
Roll out half the pie dough and drape it over a 9 or 10-inch pie pan to extend about 1.5cm over the rim. Don't stretch the dough; if it's too small, put it in the fridge for 10-15 minutes then back on the board to roll out.
Fill the pie with the apple mixture. Brush the edge of the bottom pie crust with the egg wash so the top crust will adhere. Top with the second crust and trim the edges to about 2.5cm over the rim. Tuck the edge of the top crust under the edge of the bottom crust and crimp the two together with your fingers or a fork. Brush the entire top crust with the egg wash, sprinkle with 1 teaspoon sugar, and cut 4 or 5 slits.
Place the pie on a sheet pan and bake for 60-75 minutes, or until the crust is browned and the juices begin to bubble out. Serve still warm with ice cream.