Rich and Silky Turkey Gravy

Good gravy begins with good stock. At least one day (and up to four days) before the feast, make your own rich turkey stock. (For a recipe, see Do- Ahead Turkey Stock ; in a pinch, you can use store-bought low-salt chicken broth, but the results with homemade are incomparable.) When you're ready to make the gravy, bring 4 cups stock to a boil in a medium pot. Remove from heat; keep warm.
Melt 4 tablespoons unsalted butter or turkey fat in a large heavy saucepan over medium heat. Whisk in 1/4 cup all-purpose flour and cook, whisking, for 1 minute. The roux will become smooth and golden brown. Keep whisking! Within 2-3 minutes it will be the color of café au lait and smell slightly toasted. Gradually whisk in the warm turkey stock, bring to a boil, then lower the heat so the gravy's at a bare simmer.
Now, for an herbaceous kick, add 2 bay leaves or 1 sprig thyme. For an umami boost, stir in 4 dried porcini mushrooms or 2 teaspoons porcini powder along with 2 tablespoons Madeira. With or without these upgrades, let gravy simmer until reduced by half, then remove herbs or mushrooms with a slotted spoon. Season with kosher salt and serve. Or keep the gravy warm until the turkey is finished and take it one step further…
Transfer the turkey to a cutting board and strain the drippings from the pan into a measuring cup. Skim the fat; add enough water to measure 1 cup. Place the pan across two burners set on medium-high heat. Add the drippings mixture and deglaze the pan, stirring and scraping up any browned bits with a wooden spoon. Strain into the gravy; simmer until slightly thickened, 10 minutes. Season to taste with salt and serve.