• Preheat the oven to 375°F. Line a baking sheet with foil and place in the oven to preheat as well. Remove the unbaked, prepared 9-inch deep dish pie crust from the refrigerator. Line the pie crust / pie plate with parchment paper and add pie weights or dried beans. Bake the crust for 20 minutes.
• Remove the parchment paper and pie weights or beans and set aside. Return the crust to the oven and bake another 10 minutes or until it starts to brown lightly.
• Remove from the oven and set aside to cool while preparing the filling.

To prepare the filling:

• Whisk together the sugar, cornstarch and lemon zest. Place the clean, dry blueberries in a large mixing bowl. Add the grated apple, lemon juice and sugar/cornstarch mixture. Gently toss the blueberries to combine or use a rubber spatula and gently turn to coat. Set aside until the berries start to release their juices - 20-30 minutes, while preparing the topping.

To prepare the topping:

• In the bowl of the food processor combine the flour, brown sugar, butter and granulated sugar. Pulse until combined. Remove to a small mixing bowl and using the back of a large spoon press some of the topping together to form large chunks. Refrigerate until ready to use.
• To assemble the pie, pour the blueberry mixture into the blind baked pie crust. Top with the crumble mixture spreading evenly.
• Bake on the foil lined baking sheet at 375°F for 1 hour. After 30 minutes, tent the pie with foil if starts to brown too quickly.
• Once the filling bubbles and the pie is golden brown, remove from the oven and allow to cool to room temperature.
• Store leftovers in the refrigerator.