MEANWHILE, MAKE THE TOPPING
Preheat the oven to 350°. Butter a 9-by-13-inch glass baking dish. On a lightly floured work surface, roll out the pastry to an 11-by-15-inch rectangle, about 1/8-inch thick. Trim the pastry to a 10-by-14-inch rectangle. Roll the pastry around the rolling pin and carefully unroll it in the prepared baking dish, easing it into the corners. Line the pastry with aluminum foil and fill with pie weights or dried beans. Bake the pastry for about 20 minutes, until it is lightly browned and just set. Remove the foil and weights and bake for 8 to 10 minutes longer, until the pastry is cooked through but not browned.