Pie crust

1. In a large bowl, combine flour, powdered sugar, and salt. Add cold butter cut into small cubes and rub it into the dry ingredients with your fingertips until you get a crumbly texture with small pieces of butter.
2. Pour in the ice-cold water little by little, mixing just until the dough comes together. Do not overmix. Shape into a ball, then divide into 2 equal portions.
3. Wrap each dough in plastic wrap and chill for 20 minutes to make it easier to roll out.
4. On a lightly floured surface or between parchment paper, roll out one portion of dough into a circle about 3–4 mm thick, slightly larger than your pie dish.
5. Transfer the dough into the pie dish, gently press it into the bottom and sides, and shape the edges. Prick the base with a fork, then place the crust in the freezer while preparing the filling.

Blueberry filling

1. In a saucepan, combine frozen blueberries, sugar, lemon juice, vanilla, and cornstarch.
2. Cook over medium heat, stirring regularly, until the mixture thickens and the juices become glossy, about 5–7 minutes.
3. Remove from heat and let cool completely before using. This step is important for a set filling.

Assembly

1. Pour the cooled blueberry filling into the prepared crust and spread evenly.
2. Roll out the second portion of dough and cut into strips about 2–3 cm wide.
3. Arrange half the strips over the pie in one direction, then place the remaining strips across to form a lattice pattern.
4. Press the ends of the strips into the edges to seal, trim any excess dough, and reshape the edges if needed.
5. Place the pie in the freezer for 30 minutes to 1 hour to help it hold its shape during baking.

Baking

1. Preheat the oven to 180°C (350°F).
2. Brush the top crust with beaten egg wash for a golden finish.
3. Bake for 45–55 minutes on the middle rack until the crust is golden brown and the filling is bubbling.
4. Let the pie cool at room temperature before slicing so the filling can fully set.