Preheat the oven to 375℉.

In a large blow, stir together the berries, sugar, lemon juice, lemon zest, and cornstarch until all the berries are coated.

On a lightly floured counter, roll out one of the pie crusts into a 13" circle. Transfer the dough to a 9" round pie pan. Allow the excess dough to hang over the edge of the pan.

Pour the berries into the pie pan. Dot the top of the berry filling with the cubed butter.

Roll out the second pie crust into a 12" circle. Either cut a vent into the crust and place over the pie, or cut the dough into 1" wide strips. Arrange the strips in a lattice pattern over the berries. Crimp the excess dough (top and bottom) around the edges. Brush the dough lightly with egg wash and sprinkle with coarse sugar.

Place the pie on a baking sheet and bake for 30-40 minutes, or until the crust is a light golden brown and the filling is bubbly. If you need to, shield the crust with tinfoil to prevent over-browning of the crust.

Remove the pie from the oven and allow to cool on a wire rack for at least 2 hours before serving. Serve with vanilla ice cream.