Add flour, salt, sugar in food processor bowl and pulse to combine. Add butter and process until the mixture resembles coarse oatmeal, about 10 seconds. Add ice water, tablespoon at a time through the feed tube pulsing just until the dough holds together without being wet or sticky, do not process more than about 30 seconds. Test the dough by squeezing a small amount together. If it seems crumbly, add a bit more water. Divide dough in half, form 2 disks 6-inch in diameter. Wrap each disk and chill at least 10-15 minutes.
In a medium bowl, add sugar and cornstarch whisk until completely combined. In a large bowl, add blueberries and lemon juice, toss with fingers to combine. Add the dry mixture to the blueberry mixture, toss with fingers to combine, lightly squeezing some of the blueberries. Set aside and let it macerate for about 15 minutes. Toss again with fingers to combine.
On a lightly floured piece of parchment paper, roll out one disk to 11-12-inch round. Ease dough into a 9-inch glass dish pie plate, slightly pressing it into the plate. Trim dough to a ½-inch overhang all around. Chill pie shell until firm about 15-20 minutes. Roll out remaining dough to a similar size above. Cut into 1-inch strips. Refrigerate strips for about 15-20 minutes.
Remove chilled pie shell from refrigerator and spoon blueberry filling into pie shell, mounding slightly in the center, dot with butter. Remove chilled dough strips from the refrigerator. For the lattice top, lay five strips over the filling, parallel and equally spaced from one another. Carefully fold back the second and fourth strips, and then lay another strip of dough perpendicular to them. Unfold second and fourth strips over new strip.
Fold back the first, third and fifth strips then lay another strip of dough perpendicular to them. Unfold the first, third and fifth strips over the new strip. Repeat until pie has been covered with a lattice crust.
Trim dough strips to ¾-inch of the edge of dish. Fold edges of strips and bottom dough underneath itself, creating a thicker border that rests on the lip of the dish. Crimp edges.
In a small bowl whisk together egg yolk and cream. Lightly brush dough strips with egg wash and sprinkle with sugar. Refrigerate pie until firm, about 30 minutes.
Preheat oven to 425 degrees, with rack in lower third slot. Place an empty cookie sheet into the oven.
Remove pie from refrigerator. Cover pie edges with foil. Place a piece of parchment paper on the hot cookie sheet. Place pie on the parchment-lined baking sheet. Bake for 20 minutes. Reduce oven temperature to 350 degrees. Cover pie with a piece of parchment paper. Continue baking rotating baking sheet half way through until golden brown and juices are bubbly and have thickened about 65–70 minutes. Transfer pie to a wire rack to cool completely (3-4 hours) allowing the blueberry filling to set. The pie can be kept at room temperature, loosely covered with plastic wrap, for up to 2 days.