Freeze 4 cups fresh blueberries overnight. Rinse the frozen berries in a colander by running cold water over them until they are slightly, but not completely, thawed. In a large bowl, mix 1/3 cup all-purpose flour, 3/4 cup granulated sugar, 1 teaspoon cinnamon. Mix well. Pour contents into a 9" prepared crust. Dot with 2 Tablespoons unsalted butter and 1 Tablespoon fresh lemon juice. Place a top crust over the filling, and cut slits in the top of the dough. Crimp the edges together. Brush the top with 1 beaten egg white and sprinkle with 1 Tablespoon granulated sugar. Place into a 400°F. preheated oven for 40-45 minutes, or until juices begin to bubble through slits. Remove and place on a wire rack until cooled. Serve room temperature with ice cream or a dollop of whipped cream on top.