Pre-make your pie crust and let it refrigerate for 1 hour in the refrigerator before using. Roll the first disk into a 13" circle and transfer it to a 9" wide, deep pie pan.
Roll the second crust into a 12" circle and use a pizza cutter to slice into ten 1-inch strips. In a large mixing bowl, combine 6 cups blueberries, 1 tsp lemon zest, 2 Tbsp lemon juice, 1/2 cup granulated sugar, 4 1/2 Tbsp flour, 1 tsp cinnamon and toss to combine.
Transfer blueberries into the dough-lined pie pan, mounding it just slightly in the center and keeping the edges clean of blueberry juice. Using the 10 strips of dough, create a lattice crust over the top: Place 5 strips of dough evenly over the pie, with the longer strips in the center.
Fold back every other strip halfway and place a long strip in the center perpendicular to the first 5 strips. Fold the strips back over the new line and fold back the alternate strips. Continue adding and alternating strips, then switch to the other side of the pie and continue until the woven lattice is finished. Pinch the edges to seal then crimp for a fluted pattern.
Beat together 1 egg and 1 Tbsp water and brush the egg wash over the lattice crust and edges. Bake in the center of the oven at 375˚F for 50-60 minutes, or until the crust is golden and blueberry juice is bubbling at the edges.