Preheat your oven to 400°F (200°C) and grab a 9-inch pie plate. If using frozen blueberries, there's no need to thaw them beforehand; just proceed with the next steps.

Take one sheet of pie crust from the refrigerator and gently unroll it into your pie plate, pressing it firmly against the bottom and sides.

In a large bowl, whisk together the sugar, flour, lemon juice, cinnamon, and salt, then gently fold in the blueberries until they are evenly coated.

Pour the blueberry mixture into the prepared pie crust, spreading it evenly.

From the second sheet of pie crust, cut 1-inch wide strips with a sharp knife or pastry wheel, then arrange them in a lattice pattern over the blueberry filling.

Trim any excess crust from the edges, then crimp the edges of the pie crust for a decorative finish.

For an optional golden finish, whisk together an egg and a tablespoon of water, then brush this mixture lightly over the lattice crust.

Place the pie on a baking sheet to catch any drips and bake for 20 minutes at 400°F (200°C).

Reduce the oven temperature to 375°F (190°C), cover the edges of the pie crust with aluminum foil to prevent excessive browning, and bake for another 25-35 minutes.

The pie is ready when the crust is golden brown and the filling is bubbling thickly in the center.

Let the pie cool on a wire rack for at least 2-3 hours before slicing and serving, allowing the filling to set properly.