How to Make It
Remove the vegetables and neck from the roasting pan; discard. Carefully strain the pan juices into a fat separator. Let stand 5 minutes, allowing the fat to rise to the top. Pour the juices into a large measuring cup, leaving the fat behind.
Place the empty roasting pan across 2 burners over medium-high heat. Add the wine and cook, scraping up the brown bits stuck to the pan, for 1 minute.
Pour the contents of the pan into the measuring cup of skimmed juices. Add enough chicken broth to make a total of 4 cups of liquid.
Melt the butter in a large saucepan over medium heat. Sprinkle with the flour to create a roux.
Cook the roux, whisking frequently, until deep brown, 4 to 5 minutes. Keep in mind that the darker the roux, the richer the flavor.
Whisk in the 4 cups of liquid and bring to a boil. Reduce heat and simmer until thickened, 8 to 10 minutes.
Season the gravy with ¾ teaspoon salt and ¼ teaspoon pepper. Strain just before serving. (If you do it any earlier, a skin will form on the surface of the gravy.)