Preheat the oven to 375F.

Divide the pastry in half, making one piece slightly larger than the other. On a lightly floured surface, roll the larger piece out into a 12-inch circle; transfer to a pie plate and gently fit it in, without stretching.

In a medium bowl, toss the sugar and cornstarch to get rid of any lumps of cornstarch; add the berries (if they’re frozen, don’t thaw them), and the lemon juice. Pour into the pie plate and dot with butter.

Roll out the remaining pastry, making a circle slightly larger than your pie plate. Cut rough holes for the eyes and nose, and make the mouth with the tip of a knife, without cutting all the way through. Transfer to the top of the pie and trim the excess crust around the edge of the pie plate, pinching the pastry together to seal and pressing down all the way around with the tines of a fork.

Bake for about 1 hour, or until the pie is deep golden and the juices have thickened. Serves 8.