Begin by making your double pie crust recipe. If using store-bought, let it sit at room temperature for about 15-20 minutes. If making from scratch, roll out half of the dough on a lightly floured surface until it’s about 1/8-inch thick. Carefully place it into your pie dish, ensuring it covers the bottom and sides.
In a large mixing bowl, combine the thawed blueberries, sugar, lemon zest, lemon juice, and cornstarch. Gently toss the mixture until the blueberries are evenly coated. Let it sit for about 10 minutes to allow the flavors to meld.
Pour the blueberry filling into the prepared pie crust, spreading it evenly. Dot the filling with small pieces of unsalted butter for added richness.
Roll out the second half of the pie dough and cut it into strips about 1-inch wide. Lay half of the strips across the pie in one direction, leaving gaps for the lattice. Then, carefully weave the remaining strips over and under the first set to create the lattice pattern.
In a small bowl, whisk together the beaten egg and water. Brush the lattice top with the egg wash, then sprinkle with coarse sugar for a beautiful finish.
Preheat your oven to 425°F (220°C). Place the pie on a baking sheet to catch any drips and bake for 15 minutes. Reduce the temperature to 350°F (175°C) and continue baking for an additional 30-35 minutes, or until the crust is golden brown and the filling is bubbling.
Once baked, remove the pie from the oven and allow it to cool on a wire rack for at least 2 hours. This will help the filling set up properly. Serve warm or at room temperature with whipped cream or vanilla ice cream!
