Make the Pastry Dough:

1. In a food processor, add flour, sugar, salt and cubed butter. Pulse mix on and off for 1 minute, until the flour mixture turns into a small breadcrumb-like consistency.  
2. Drizzle ice water into the mixture (ice water is the key here). Close the lid and continue to pulse mix on and off for another 1 minute. If you squeeze the crumbs together and they stick together, that means the crumbs are good to go.
3. Transfer the dough (crumb-like) into a large ziploc bag and squeeze with your hands to bring all the loose crumbs together until it turns into a nice and smooth dough ball.
4. Divide the dough ball in half and flatten to form 2 equal discs. Wrap the discs separately in plastic wrap and refrigerate for at least 1 hour.

Assemble the Pie:

1. In a large mixing bowl, combine blueberries, flour, sugar, lemon juice, lemon zest, and cinnamon and mix together.  Set aside for assembling.
2. Unwrap each dough disc and place in between 2 pieces of parchment paper or plastic wrap. Roll each dough disc into 12-inch circle using a rolling pin.
3. Transfer the first dough disc onto a 9-inch pie pan and gently press down to form into the bottom pie crust.
4. Slowly pour the blueberry mixture into the dough-lined pie pan and use a spatula to spread them evenly across.

Create the Lattice Top:

1. Slice the second dough circle into 10 strips, measuring 1-inch wide. Save the dough scraps to the side.
2. Place 5 strips of dough on top of the blueberry filling, evenly placed 1-inch apart (make sure to use the longer strips in the centre and shorter strips for the edges).
3. Fold back the 2nd and 4th strip halfway and place the longest strip in the centre, perpendicular to the first 5 strips. Place the 2nd and 4th strip back over that long strip.
4. Fold back the 1st and 3rd and 5th strip halfway and place a slightly shorter strip 1-inch away. Place the 1st and 3rd and 5th strip back over the shorter strip.
5. Continue adding and alternating strips to complete the lattice top crust.
6. Press edges together and crimp with your fingers to seal. You can place the scraps along the edge and pinch them into the edges to seal.
7. Gently brush the egg wash over the lattice crust and edges. If your oven is not ready at this point, store the assembled pie in the fridge to prevent the pie crust from disintegrating (the butter in the dough melts quickly at room temperature).

Bake the Pie:

1. Preheat the oven to 375 F.
2. Transfer the blueberry pie pan into the oven and bake for 50 minutes until the top crust is golden brown.
3. Leave the blueberry pie in the pan at room temperature for 1 hour before serving.
4. Serve a slice of blueberry pie with a scoop of vanilla ice cream.