"This apple slab pie is best served straight from the oven but if you're in a pinch, it can also be made in full one day in advance. Make the pie as instructed, leaving it in the baking sheet, covered with foil, at room temperature or in a cool room (we kept it in the garage), then reheat it at 300° F until warmed through (about 20 minutes). You can crank the broiler on in the last couple of minutes to crisp up the top crust if you wish - just watch it carefully to avoid burning the buttery crust.Alternatively, you could assemble the whole pie up to one day in advance and keep it in the fridge until you're ready to bake it off...."