Not sure exactly what you mean by authentic Italian (the word authentic always trips me up), but I would check out Dearborn Italian Bakery on Ford Road. I'm 99 percent sure they have take-and-bake pizza. From what I've heard, the original owners retired, so I'm not sure if it's the same quality.
You might also try La Cantina Market on Telegraph, between Ford Road and Cherry Hill in Dearborn. They used to have a lot of take-out items, although I'm not sure if they did pizza. They do a lot of importing of products from Italy and always had great meats and cheeses, so if they do pizza I'm betting it would be great. If not, they might have insider advice on where to get it.
There also used to be a fresh pasta/pizza shop on Ford Road, not far from DIB, but the name of it escapes me now. Not sure if it's there anymore, but it would have opened late 90s or early 2000s. Anyone help?
Not an answer to this question (I don't think they sell the uncooked pizzas, although you could always ask), but since you're interested in authentic Italian foods just wanted to make sure you had visited Silvio's pizzeria in Ann Arbor, on North University near State. Italian to the bone, including the uncannily gorgeous daughter working the register if you're lucky. Also organic (the pizza, not the daughter). Their pizza, BTW, is best if you eat it right there or take it home and reheat it in a very hot oven.