I placed a 14 lb young Round Hill Frozen Basted Turkey in a pan, and roasted it inside an oven.
After it was roasted, there was quite an amount of oily liquid left in the pan. Is this liquid worth keeping, and for what purpose?
Before you use the drippings, taste them. If they taste good on their own, they will be great for gravy. Often, the oil left in the pan after roasting turkey is used to make the roux to thicken gravy to go with that turkey. If it looks like all oil, you can use it as such.
Especially since the turkey was pre-basted, the drippings might be a mixture of oil and juices. Pour the drippings into a clear container so you can see just how much is oil and how much is juice. Scoop off the oil and cook it (and added butter as necessary) on the stove (preferably in the roasting pan) with an equal (roughly) amount of flour.
To make a roux gravy, the basic formula is 2 tablespoons fat, 2 tablespoons flour, and 1 cup of liquid to equal 1 cup of gravy.
Quote from about food which meshes with my own experience.
As you cook the flour and oil to a medium brown, try to scrape up any brown bits stuck to the pan. Those are huge flavor bombs. The liquid portion of the drippings poured off can be added with the broth that is the liquid part of the gravy.
The above link leads to more detailed instructions.
I would pour all the juices into a jug and refrigerate it. The fat will solidify on top, and I would remove that to use for roasting potatoes, saving the juices below for gravy making, with boiling water and gravy granules - quick and simple. This is what I did when cooking roast dinners for 40 to 100 customers every Sunday at my traditional English pub for a couple of years. People used to comment regularly on how tasty the gravy and potatoes were.
Im not so sure about a pre-basted turkey as I reckon there will be hydrogenated fats in there. However if you're roasting a fresh free-range bird this is for you! The turkey drippings (or fat, think chicken fat 2.0!)i is a combination of both fat and meat juices from the roasting and is absolute gold-dust when it comes to flavour!!
We usually pour it into a heat-proof jug and allow it to cool. You can use a couple of spoonfuls to pour over your stuffing to finish it off with flavour and ditto for roast potatoes but not too much as it has a high water content which can splash and burn easily in the oven causing smokiness.
The real treat is when heating up leftovers the next day or two, spoon over a few spoonfuls onto sliced meat, stuffing and even potatoes. It will add lots of good tasty extra taste.
BUT the BEST thing we use it for is for making fried bread for that post-Christmas fry-up. Slice some fresh white bread (on the thick side) Heat a little olive oil in a non-stick pan. Spoon in about three dessertspoons of turkey fat. It will sizzle and splash, so immediately, place your bread on top and move it around the pan to capture all that wonderful taste. Lower heat slightly and allow it to brown somewhat (watch out it may burn easily), flip it over and toast the underside a little (mostly for texture) Then place on a warmed plate, under a warmed grill. Do a couple slices and serve hot. Sprinkle with salt and enjoy. I guarantee you won't bother with the rest of the fry-up once you've tasted this. You may run out of bread!! A Christmas treat for us from my Grandmother's kitchen and we all love it to pieces - we fight over the last bit!!