Preheat the oven to 375°F (190°C).
In a large bowl, combine blackberries, sugar, cornstarch, lemon juice, vanilla extract, cinnamon, and salt. Mix well and let sit for 10 minutes.
For the crust, mix flour and salt in a large bowl. Add cold butter and use a pastry cutter or hands to combine until the mixture resembles coarse crumbs.
Slowly add ice water, one tablespoon at a time, until the dough holds together.
Divide the dough into two portions, roll out one portion, and place it in a 9-inch pie dish.
Pour the blackberry filling into the crust and spread evenly.
Roll out the second portion of dough and place it over the filling. Crimp the edges and cut slits for ventilation. Alternatively, create a lattice pattern.
Brush the top crust with an egg wash and sprinkle with coarse sugar.
Bake for 50 minutes or until the crust is golden brown and the filling is bubbling.
Let the pie cool for at least 20 minutes before serving.