Insert the dough blade attachment into the KitchenAid 9-cup Food Processor. Add the flour, salt, butter and shortening. Close and secure the lid, then pulse 8-10 times. Remove the food pusher from the feed tube and add 1 tablespoon of ice water at a time, pulsing after each addition; then, continue to pulse another 5 to 6 times, or until mixture looks moist.
Remove the dough mixture from the work bowl into a larger mixing bowl. Gently press the dough against the sides of the bowl and gather all the crumbs into a ball. Flatten the ball into a disc, sprinkle both sides with a bit of flour, and wrap the dough in plastic wrap. Rest and chill the dough for 30 minutes in the refrigerator.
Blind bake the crust. Lightly flour your surface and roll the dough into a large circle 6mm thick. Use the rolling pin to roll the dough up and then lay the round into the pie plate. Trim off excess dough, crimp the edges of the dough, and prick the surface with a fork. Then, place the prepared pie crust into the freezer to thoroughly chill before baking (about 20 minutes). While crust is chilling, position the oven shelf in the lower third of the oven and preheat the oven to 218°C degrees.
When the crust is thoroughly chilled, tear a square of tin foil and butter a circle at the center 5cm wider than your pie plate. Place the buttered side down onto the chilled crust and press the foil completely flush against the sides. Cover the surface of the pan with ordinary dried beans (or baking weights if you have them) and bake the crust for 15-18 minutes, or until sides begin to brown. Remove the crust from the oven and gently remove the foil and beans. Reduce the oven temperature to 190°C degrees and return the crust to the oven for another 4-6 minutes. When crust is golden, remove it from the oven and set aside to cool on a wire rack.
Make the filling. Insert the shredding disc into the food processor. Close and secure the lid, and turn to high. Insert the zucchini into the food tube and use the food pusher to push it into the shredder. Remove the shredded zucchini from the work bowl and put it into a mesh strainer placed over a bowl. Sprinkle the zucchini with a bit of salt, stir to coat evenly, then set aside.
Replace the shredding disc back into the food processor. (No need to clean the work bowl out.) Close and secure the lid, and turn to high. Slice the cheese into blocks that will fit into the food tube, then insert the cheese into the feed tube and use the food pusher to push it into the shredder. Remove the shredded cheese from the work bowl into a larger mixing bowl.
Insert the whipping disc into the food processor. (No need to clean out the work bowl.) Add the eggs, milk, cream, salt, pepper and garlic powder. Close and secure the lid, then turn to high and whip the mixture for 10-12 seconds. Pour the mixture into the bowl with the cheese, and add the chopped parsley, fresh thyme, and lemon zest.
Use your hand to squeeze the water from the zucchini, and press it against the mesh strainer to get it as dry as possible. Add the zucchini into the egg mixture, stir to fully incorporate all the ingredients. Set the prepared crust on a baking sheet, then pour the egg mixture into the pan. Bake the quiche for 30-35 minutes, or until the center is set, puffy and lightly golden. Use a pie shield for the first 20 minutes of baking (see chef’s notes) to prevent the crust from over-browning. Allow quiche to cool on a wire rack for at least 30 minutes before serving.