Preheat oven to 375°F (190°C).
In a mixing bowl, combine flour and butter until the mixture resembles coarse crumbs. Gradually add ice water until dough forms.
Divide dough in half, shape into disks, and refrigerate for 30 minutes.
Roll out one disk and fit into a pie dish. Set aside.
In another bowl, mix blackberries, sugar, cornstarch, lemon juice, lemon zest, and vanilla extract.
Pour filling into the pie crust. Roll out the second disk of dough and place over the filling. Seal and crimp the edges.
Cut slits in the top crust to allow steam to escape.
Bake for 45 minutes or until the crust is golden brown and the filling is bubbly.
Let cool before serving.