In a large mixing bowl, whisk together the flour, salt and cinnamon.

Toss the cold cubed butter into the dry mixture. Squeeze each piece of butter between your fingers and your thumb to flatten and break it down a bit. The butter pieces should roughly be the size of half a walnut.

Add the ice cold water one tablespoon at a time and mix with a fork until it holds its shape when squeezed in the palm of your hand.

Divide the dough into a larger disc and a slightly smaller disk. Wrap both discs individually in plastic cling wrap and refrigerate for at least 1 hour.

On medium heat in a large saucepan, cook the berries, lemon juice, lemon zest, cinnamon and granulated sugar for about 10 minutes, until the berries release their juice.

Stir in the cornstarch and increase the heat to high. Boil for one minute, then remove the saucepan from the heat. Let cool to room temperature to thicken fully.

Grease a 10-inch pie dish. Preheat the oven to 400°F.

On a lightly floured surface, roll out the larger pie disc until it will fit into your pie dish.

Gently transfer the pie crust into the pie dish.

Pour the thickened room-temperature berry filling into the pie crust. Store it in the fridge again while you prepare the top pie crust.

On a lightly floured surface, roll out the smaller disc of pie crust. Use cookie cutters to cut out shapes from the pie crust.

Add the cut-out shapes of pie crust on top of the pie filling.

Whisk the egg in a small bowl, then brush onto the pie crust.

Bake for 20 minutes, then reduce the temperature to 375°F and bake for another 45 - 60 minutes, until the crust is golden.

Allow to cool for at least 30 minutes, then slice up and enjoy!