You can, actually. You won’t be able to do anything super fancy to a frozen turkey but you can baste or season it once it starts cooking. And be aware that the likelihood of dry white meat increases with a frozen bird.  This is a pretty straightforward method−put that frozen bird in a roasting pan and cook it at 325℉ until all parts reach 165℉. You’re looking at about 50% more cooking time because it’s frozen, though. It’s safe to do and even USDA approved. Cooking a frozen turkey can only be done in the oven−DO NOT grill or deep-fry a frozen turkey, it’s dangerous and not worth the risk. And don’t stuff a frozen turkey, make a separate dressing instead.