In a large bowl, stir together the flour and salt.
Cut or grate the butter into small pieces into the flour mixture.
Use a pastry blender or sturdy fork to combine the butter and flour until the mixture becomes crumbly.
Mix the ice water into the bowl a tablespoon at a time until the mixture begins to form a dough.
Separate the dough into two equal portions. Form the dough portions into discs, then wrap them in plastic wrap and refrigerate for at least 30-60 minutes.
Remove one disc of the pie crust and place it onto a well-floured surface. Heat your oven to 350 °F (177 °C)
Roll the dough out into a 10-11" square, roughly ⅛ inch thick.
Carefully drape the rolled dough over an 8x8 square cake pan or casserole dish, then press the dough into the bottom and sides of the pan. Use a knife to cut off any excess dough hanging over the edges of the pan.
Use a fork to prick the dough all over in order to allow trapped air to escape from under the crust as it bakes. Line the crust with aluminum foil and fill with pie weights, uncooked rice, or beans, then bake for 10-12 minutes.
To make the filling: Add the blueberries, sugar, lemon zest, and cornstarch to a bowl. Toss with a spoon or fork to coat the berries evenly.
Remove the par-baked pie crust from the oven and discard the pie weights. Spoon the blueberry filling mixture into the crust. Spread the filling evenly using a spoon.
Remove the other pie crust disk from your refrigerator and, again, roll it into a square over a well-floured surface.
Using a sharp knife or pastry cutter, slice the dough into long strips, about ½-¾ inch wide.
Arrange the pastry strips over the blueberry pie filling and weave them into a lattice topping. Use a knife to cut off any over-hanging dough. Add a braid around the edges or create a scalloped edge if desired.
Beat the egg and cream or water together, then gently brush the mixture over the top of the pie crust. Generously sprinkle the additional sugar over top.
Bake for 40-50 minutes or until the crust is golden brown and the filling is bubbly. Cut into squares and serve
Notes
I used Wyman’s brand wild frozen blueberries because I love their intense flavor and soft texture. You can use regular blueberries if desired, fresh or frozen.If using fresh berries, keep your baking time closer to the 40 minute mark, and increase the bake toward the 50 minute mark if using frozen berries.Pie dough is easiest to handle when cold and firm. If needed, refrigerate at the crumb or dough in between steps. You can substitute 2 tablespoons of flour for the cornstarch in the filling if needed.The lattice topping is beautiful, but completely optional. Alternatively, you can place the 2nd rolled dough sheet over the filling and cut 3 slits into the middle before placing your pie into the oven, to allow air to escape while baking.To prevent the braided or scalloped edge from burning, cover the edges of the pie with foil before baking.Allow the pie to cool slightly, then cut into slices.Serve with a scoop of vanilla ice cream, a dollop of fresh whipped cream, or eat it as is.This recipe can also be made in a 9-inch square pan or a regular 8-9 inch round pie dish. To serve a larger crowd, double the recipe and use a 9x13 inch casserole dish.