In a medium bowl, combine the blackberries, sugar, cornstarch, lemon juice, lemon zest, cinnamon, nutmeg, salt, and vanilla. Stir until evenly combined.
Pour the blackberry mixture into the prepared pie crust.
Scatter the butter cubes over the top of the blackberry mixture.
Bake for 30 minutes, or until the crust is golden brown and the filling is bubbling.
Let cool before serving.
Interesting Facts
Blackberry-lemon pie is a classic American dessert.
Lemon is a natural preservative, so this pie can be stored in the refrigerator for up to 5 days.
This pie is a great way to use up summer berries before they spoil.