Delta Blues Blackberry Pie

1/2 cup granulated sugar
2 tablespoons each: brown sugar, cornstarch
Juice and zest of 1/2 small lemon
4 cups fresh or frozen (defrosted and drained) blackberries
2 unbaked 9-inch pie crusts
1 egg
1 tablespoon milk

Heat oven to 400 degrees. Position rack in the lowest third of the oven. Stir together white and brown sugar, cornstarch, lemon juice and zest in a large bowl. Add blackberries; toss with your hands to coat blackberries with sugar mixture. Set aside. Line a pie pan with 1 crust, pressing edges to lightly flute; prick holes in the bottom crust with fork tines; set aside. Drain filling of any excess liquid, reserving sweetened blackberry juice for later use, if desired. Spread filling over prepared crust.Form a lattice crust with 1/2-inch strips of the second pie crust; whisk together the egg and milk in a small bowl; brush lightly over strips with a pastry brush.

Bake 30 minutes; check pie crust to see if the edges are browning too quickly. Add strips of foil to cover edges, if desired. Bake until crust browns evenly and filling bubbles, about 20-25 minutes.