Rub the shortening into flour until the mixture resembles fine breadcrumbs. Keep the ingredients as cold as possible and rub using fingertips only.
Add enough ice water to form a dough that comes cleanly away from the bowl.
Wrap in plastic and allow to rest in the fridge for at least 30 minutes while you prepare the filling.
Heat the pizza stone and oven to 375°F Using the pizza stone prevents the pastry from becoming soggy.
Sun-dried tomato layer - Combine the feta, ricotta and sun-dried tomatoes and blend in a food processor.
Add the egg and continue to blend until a paste is formed.
Mix in grated asiago cheese and pine nuts and place in covered bowl and set aside in fridge.
Spinach layer - thaw and drain spinach. Dry the spinach with kitchen towels, it is important this is not too moist or the pastry will become soggy.
Combine spinach, thinly sliced shallots, cayenne pepper flakes and Italian herbs.
Roll out the 2/3 pastry to approximately a 10" circle. Lightly dust the cake tin with corn flour.
Line the cake tin (7" diameter, 3" deep springform pan) with the rolled pastry. Brush the pastry with egg white and allow to air dry. This will also help to prevent the crust from becoming soggy.
Layer half mozzarella in to the bottom, follow with half the sun dried tomato mixture, next spinach layer, then roasted red peppers. Place all of the artichokes in the next middle layer and repeat with the other half. Make sure the peppers and artichoke are dried with kitchen towel to prevent crust sogginess.
You can layer the torta whatever way you like - be creative!
Roll out the remaining pastry and cut into 1" strips. Place over the torta to create a lattice and seal with the bottom crust.
Brush the top of the pastry with milk.
Bake at 375F for 50-60 minutes until golden.
Allow to cool before removing from the pan. You can invert the pan into a plate and repeat to turn the correct way around. Best served at room temperature.