Preheat the oven to 350°F
Place the apple pie on a baking sheet
Cover the crust loosely with foil if needed
Bake for 15 to 20 minutes
Check that the filling is hot in the center
Let the pie rest for a few minutes before serving
For a single slice, microwave on medium power for 20 to 30 seconds
For a crispier crust, reheat slices in a toaster oven at 350°F for 5 to 10 minutes