The safety of stuffing cooked inside the turkey gets debated this time every year. The fear is that if the turkey and the stuffing do not reach a temperature of 165 °F, there is a risk of salmonella contamination. No one will be thankful if they get a touch of food poisoning from contaminated stuffing, no matter how juicy and flavorful it is.
The USDA recommends cooking your stuffing outside of the turkey and making sure that it reaches a temperature of 165 °F even when cooked outside the bird.
For optimum safety, stuffing a turkey is not recommended. For more even cooking, it is recommended you cook your stuffing outside the bird in a casserole. Use a food thermometer to check the internal temperature of the stuffing. The stuffing must reach a safe minimum internal temperature of 165 °F.
If you choose to stuff your turkey, the ingredients can be prepared ahead of time; however, keep wet and dry ingredients separate. Chill all of the wet ingredients (butter/margarine, cooked celery and onions, broth, etc.). Mix wet and dry ingredients just before filling the turkey cavities. Fill the cavities loosely. Cook the turkey immediately. Use a food thermometer to make sure the center of the stuffing reaches a safe minimum internal temperature of 165 °F.
There’s a passionate discussion in the comments on Serious Eats about stuffing that shows just how intense people can get about the entire to stuff or not to stuff debate. One reader had a suggestion in the comments that seems to make perfect sense to me.
Tmj529 has this advice:
Stuff the bird, get the bird to temp, pull it, unload the stuffing into a separate baking dish and then finish the stuffing while the bird rests.