Step 1

Roll out one of the pie crusts to a diameter of 12 to 13 inches and transfer it to a 9-inch pie plate. Snug it into the corners of the pan. Transfer the pie pan to the fridge and chill the crust for 30 minutes.

Step 2

Preheat the oven to 425°F while the crust is chilling.

Step 3

Combine the blueberries, 3/4 cup to 1 cup of the granulated sugar, 3 tablespoons cornstarch, lemon zest, and lemon juice in a small bowl. Use more sugar if your berries are very tart and more cornstarch if your berries seem very juicy or if you prefer a more firm pie filling. Stir until the sugar dissolves into a gooey coating and let the berries macerate on the counter 15 to 30 minutes.

Step 4

Remove the pie crust from the fridge and pour the berries inside. Roll the second pie crust to a diameter of 11 to 12 inches and gently lay it over the top of your pie. Trim the edges to make them even, then tuck the edges under themselves and crimp. Cut a few vent holes in the top pie crust and brush all over with the egg yolk.

Step 5

Transfer the pie to a baking sheet (to catch any drips) and bake in the oven for 15 minutes. Turn down the oven temperature to 350°F and continue baking for another 30 to 40 minutes, until the berry juices are bubbling and the top crust is golden brown. If the edges of the pie are browning faster than the middle, cover the edges with tin foil.

Step 6

Remove the pie from the oven and let it cool for at least 4 hours before serving. If serving the next day, leave the pie on the counter and cover with a cake dome or very large bowl once it is cool.