Updated: Jan 8, 2021
12 tablespoons (1 1/2 sticks) very cold unsalted butter
3 cups all-purpose flour
1 tablespoon maple sugar
1 teaspoon kosher salt
1/3 cup very cold vegetable shortening, such as Crisco
1/2 cup ice water
Cut the butter in 1/2-inch dice and return it to the refrigerator while you prepare the flour mixture. Place the flour, sugar, and salt in the bowl of a food processor fitted with a steel blade and pulse a few times to 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 the machine until the dough begins to form a ball. Dump out onto a floured board and roll into a ball. Wrap in plastic wrap and refrigerate for 30 minutes.
Roll dough until generously larger than the cast iron pan. Fold the dough in half, ease it into the pan without stretching at all, and unfold to fit the pan.
¾ cup maple sugar
4 tablespoons cornstarch
¼ teaspoon salt
½ teaspoon ground cinnamon
6 cups fresh blueberries
splash of lemon juice
1. Preheat oven to 375 degrees F (190 degrees C).
2. Mix sugar, cornstarch, salt, and cinnamon, and sprinkle over blueberries.
3. Pour berry mixture into the crust in the pan. Fold remaining crust over to top of the pie, leaving a few inches uncovered in the centre.
4. Bake pie on lower shelf of oven for about 50 minutes, or until crust is golden brown.