How long and at what temp should I roast a 15 pound turkey breast?

Hi Gretchen, you can get the turkey done early and let it rest. No need to have it come out of the oven right before you are going to serve it. give yourself ample time and let it rest on the counter after it's done. A little hot broth poured over the slices and the hot gravy will warm the meat up. Don't sweat it and pour yourself a glass of wine...

Here is a good cheat sheet we put together: https://food52.com/blog/18372-the-essential-numbers-a-guide-to-times-and-temps-for-cooking-your-bird