Do not thaw first because you are likely to get a soggy crust if you do! To reheat already baked pie - Place in the oven at 350 degrees Fahrenheit for about 15 minutes. Heat until it is heated through, remove and enjoy! To cook a frozen unbaked apple pie - Place in the oven heated to 425 degrees Fahrenheit and cook for 25 minutes before dropping the oven temperature to 350 degrees. Continue baking for about 40-50 minutes, until it is cooked through and the crust is a nice golden brown.