Make the pie dough, rolling out a top and bottom crust. Place the bottom crust into the 9″ pie pan.
Preheat oven to 400° F/200° C and set rack in the lower third of the oven.
Combine sugar, flour, cornstarch, and cinnamon in separate bowl and set aside.
Put wild blueberries in a glass bowl and microwave on high to thaw, about 1 to 2 minutes. Put thawed berries into a mesh strainer and strain well, reserving 2 tablespoons of the liquid. This is important because too much liquid will render a soggy pie.
Combine dry ingredients and wild blueberries in large mixing bowl. Stir gently until mixture is well-blended while adding the strained juice.
Pour into the lined pie pan. Add the top layer and crimp the edges. Spritz edges and top with cold water. Sprinkle with sugar and cut three slits to vent the top crust.
Bake 40-50 minutes or until filling begins to bubble. Serve at room temperature.