Preheat oven to 400* F. Line a baking sheet with parchment paper.
After the pie dough has chilled, make the blackberry filling by combining blackberries, sugar, cornstarch, lemon juice, vanilla extract, and lemon zest in a large bowl. Use your hands to toss the mixture together until everything is evenly coated. Set aside.
3 Cups Fresh Blackberries, ⅓ Cup Granulated Sugar, 1 Tbsp Cornstarch, 1 Tbsp Lemon Juice, 1 tsp Vanilla Extract, 1 tsp Lemon Zest
Lightly flour a work surface and a rolling pin and roll the pie dough into an 11-inch circle. Then, transfer the pie dough to a parchment-lined baking sheet.
Pile the blackberry filling into the center of the pie dough, leaving a 2 -inch border around the outside of the dough. Then, fold the border inward, crimping the dough as you go around, forming the crust of the galette. Sprinkle the crust with granulated or turbinado sugar.
2 tsp Granulated Sugar
Bake the galette in a 400*F oven for 35-40 minutes, or until the filling is bubbling and the crust is golden brown.
Allow the galette to cool for at least 45 minutes before slicing and serving.