Pour the turkey drippings into a large measuring cup and let it rest until the fat comes to the top. Spoon off most of the fat and discard. Add enough stock to the measuring cup to equal 4 cups of stock/drippings combined.
Place the roasted pan you roast the turkey in over the stove on medium high heat. Add the butter to the roasting pan and scrape up any brown bits that are stuck to the bottom of the pan.
Add the flour to the pan and whisk everything together until you form a roux. Continue to whisk until the roux is a dark brown color and fragrant.
Add the stock/dripping mixture to the roux and whisk to combine.
Turn the heat to high and bring the liquid to a boil while still stirring. Once the liquid reaches a boil, reduce the heat to medium and stir occasionally until the gravy is as thick as you'd like it.
Once the gravy is thick, serve it immediately or keep it over very low heat until you are ready to serve. If the gravy develops a thin film on the top, just give it a quick whisk. Adjust salt and pepper if needed, but be sure to taste first as the drippings can be salty and you might not need any excess salt.