A woven lattice makes a striking top for a blueberry pie, especially colorful fruit. The open weave allows a peek at the filling and lets steam escape as the pie bakes. The process of weaving the top is easy to follow — cut the dough into strips, preferably with a fluted pastry wheel, and arrange them on top of the filling. This pie and many others with juicy berry fillings are thickened with cornstarch, which has stronger thickening properties than flour (a more appropriate choice for less juicy apples or pears). You may want to adjust the amount of thickener if the berries are particularly juicy, or if you prefer a firmer or looser pie filling.
Preheat oven to 400 degrees. On a lightly floured surface, roll out 1 disk of dough to a 13-inch round, about 1/8-inch thick. Fit dough into a 9-inch pie plate.
In a large bowl, toss together berries, granulated sugar, cornstarch, cinnamon, and lemon juice until combined. Pour mixture into pie plate, piling in center.
On a lightly floured surface, roll out remaining disk of dough as in the first step. To make lattice, cut dough into ten 1-inch-wide strips using a fluted pastry wheel. Lightly brush edge of dough in pie plate with water. Carefully arrange dough strips on top, weaving to form a lattice. Trim dough to a 1-inch overhang. Fold edges under as desired, and crimp with a fork. In a small bowl, whisk together egg yolk and cream for egg wash; brush on top of dough strips and edge of pie shell. Generously sprinkle with sanding sugar. Refrigerate or freeze pie until firm, about 30 minutes.
Transfer pie plate to a parchment-lined rimmed baking sheet, and bake until crust begins to brown, about 20 minutes. Reduce heat to 350 degrees. Continue baking until crust is deep golden brown and juices bubble, 55 minutes more. (If crust browns too quickly, tent pie with foil.) Transfer pie to a wire rack; let cool completely, at least 3 hours, before serving.