The perfect flaky pastry for pie

Ingredients:

• 165 g very chilled unsalted butter
• 3 cups premium flour
• 1 teaspoon coarse salt
• 1 tbsp. sugar
• 1/3 cup very cold margarine
• 6 - 8 tbsp (about 0.5 cup) ice water

Preparation:

1. 22 cm base for a closed pie:
   
   Cut the butter into cubes and refrigerate while you prepare the flour mixture. In the bowl of a food processor fitted with a steel blade, combine the flour, salt, and sugar and pulse several times to evenly distribute the mixture. Add the butter and shortening. Pulse 8-12 times until the butter is the size of peas.
2. With the processor running, pour ice water into the feed tube and pulse until the dough begins to form a ball.
3. Place the dough on a floured board and form it into a ball. Wrap in plastic wrap and refrigerate for 30 minutes.
4. Cut the dough in half. On a well-floured board, roll each piece into a circle, working from the center outward, turning and dusting the dough with flour to prevent it from sticking. Fold the dough in half, transfer it to the pie pan, and unfold. Repeat with the top crust.