Preheat oven to 375°F. Place rack in center of oven.
Roll out the bottom pie crust a circle that is about 5-8 cm (2-3") bigger than the pie plate and approx. 2-3 mm thickness. Place in pie plate and press to form.
To make the egg wash mix the egg together thoroughly. brush the edges of your pie crust with egg wash and pour in the blueberry filling.
Roll out the top slightly bigger than the pie plate. Fold in half and cut vent holes by making 3 slits on an angle. Place the folded edge in the center of the pie and unfold. Press the edges together.
Trim edges with scissors so there is about 1.5 cm (1/2") overhang. Fold edge under to create a lip.
Using the thumb and forefinger of one hand and the forefinger of the other pinch "V" shapes around the edge. With a floured fork press down the outside "V"s to make a decorative pattern (optional). See photos above.
Egg wash the entire top and edges of the pie and sprinkle with granulated sugar.
Place the pie on a parchment lined tray to catch the drips
Place in preheated oven and bake for one hour checking after 40 minutes to see if edges are browning too much. If they are, lower oven temperature to 350°F and/or cover edges with foil.
After one hour check to see if the filling has nicely bubbled out and the crust is very golden brown. If you think it could bake for another 5-10 minutes without getting too dark, do it.
When done remove from oven and let stand for a minimum of one hour but preferably overnight.