Unroll and cut out anywhere from 4 1/2"-5" circles from the pie crusts. (I used a small size bowl.)
Combine the cornstarch, frozen berries, and sugar. Set aside.
Sprinkle chocolate chips and spoon about 1/4 cup of the berry mixture over the center of the crusts. Fold in the outer edges of the crust inwards, sealing in the filling. Brush edges with milk and sprinkle with granulated sugar.