For each 2 cups gravy desired - use 3 tablespoons fat, 3 tablespoons all-purpose flour, and 2 to 3 cups of liquid (depending on how thick you want your gravy.)
After you have removed the turkey from the oven and set it aside to rest, place roasting pan (with the drippings and the 3 tablespoons of fat) over two (2) burners on your stovetop over medium heat (always make the gravy in the same roasting pan you used to roast the turkey).
Before making the gravy, heat the liquid (juices) you will be using until just boiling, then reduce heat to low to keep the liquid warm.
No More Whisking Lumps out of the Gravy Mixture - Make a Slurry or Roux:
In a separate container with a lid, shake together the all-purpose flour needed and about 2 cups cool water (or use food processor to blend roux.) Adding this thickened slurry (flour mixture) to the reserved pan juices helps to prevent lumps from forming when making your gravy. I always make a little extra of this flour/water mixture just in case I need it.
Once the liquid, drippings, and the fat in the roasting pan are lightly bubbling, slowly add the above slurry mixture to the gravy pan, stirring constantly. When the mixture starts to thicken, immediately stop adding the remaining flour mixture. You may not need to use the the entire flour mixture depending on how much or little drippings were in the pan. If lumps do develop, you should be able to use a wire whisk to remove them.
Once the slurry mixture is whisked in the gravy, if the gravy seems to thick, just whisk in additional water, a little at a time until desired consistency is reached.
Cooking the Gravy: Simmer gently about 10 minutes to cook the flour all the way through (undercooked flour gives off a raw taste). Add salt and pepper (and any other seasonings you desire) to taste. You now have perfect turkey gravy!
Serving the Gravy: Pour the gravy into a warmed sauceboat, gravy boat, or wide-mouthed pitcher for serving. Remember that gravy will continue to thicken after it has been removed from the heat. Since I usually make a large amount of gravy for my family, I have found that glass beer pitchers make a good serving container. Always place a plate under the serving container to catch any drips.
* See below on how easy it is to make Gluten-Free Turkey Gravy.
** Use the reserved poultry juices from the turkey with either vegetable juice, potato juice (from boiling potatoes when making mashed potatoes), prepared turkey/chicken stock, and/or water. I always save some of the water from boiling the potatoes. Any type of liquid can be added to make gravy, but always use the juices/drippings from the roasting pan and prepared turkey stock (see above) to make your turkey gravy. Add other liquids as needed for flavor and quantity of gravy. I like to make a Homemade Chicken Stock in advance of Thanksgiving to use in the gravy.
*** If you don't have enough fat from the turkey, add some butter.
Perfect Turkey Gravy Recipe - Giblet Gravy Recipe: https://whatscookingamerica.net/Menu/TurkeyGravy.htm