Prepare 2 traditional pie crusts for the top and bottom of the pie and place 1 pie crust into a 9 inch pie plate. (Click here for pie crust recipe). Make the filling—in a large mixing bowl, combine the blueberries, sugar, flour, cornstarch, cinnamon, lemon juice, and lemon zest together until a few berries burst and set aside.
Preheat the oven to 425F. While the oven preheats, roll out the dough in a 12-inch diameter circle and place into a 9x2 pie dish. Pour the filling into the dish and dot with butter on top and set aside.
Roll out the second disc of pie dough into a 12-inch diameter and use a pastry wheel to cut the desired number of strips for a lattice pie crust. Weave the pastry strips into a lattice pattern then flute or crimp the edges with a fork. Brush the top of the pie crust with the egg wash and sprinkle with the coarse sugar.
Bake at 425F for 25 minutes, then reduce the heat to 375F. Use a pie crust shield or aluminum foil to prevent overbrowning. Bake the pie until the filling bubbles over, about 45 minutes. Remove the pie from the oven and place on a cooling rack, allow to cool for at least 4 hours before slicing and serving. Serve with vanilla ice cream.