• Prep the pan: Preheat the oven to 425°F. Arrange the turkey pieces, onion, carrots, celery, and garlic in a large metal roasting pan or in a 9 x 13-inch pan. Drizzle with olive oil, season with salt and pepper, and toss to coat.
  
• Roast: Roast, uncovered, for about 1 hour, turning the turkey and stirring the vegetables halfway through. The turkey should be well browned, and the vegetables should have caramelized edges.
  
• Transfer: Move the turkey and vegetables to a Dutch oven or large pot.
  
• Deglaze: While the pan is still warm, carefully pour in the white wine. Scrape the bottom of the pan with a wooden spoon to loosen the browned bits. Pour the wine, drippings, and browned bits into the Dutch oven.
  
• Simmer the stock: Add 5 cups of the broth, the thyme, sage, and bay leaf. Bring to a boil, then reduce the heat to low. Simmer gently, uncovered, for 45 to 60 minutes.
  
• Strain and skim: Pour the stock through a fine-mesh sieve into a large bowl or measuring cup, pressing gently on the solids. Discard the solids and skim the fat from the surface. Add enough of the remaining broth to measure 4 cups total.
  
• Make the roux: Melt 3 tablespoons of the butter in a large saucepan over medium heat. Add the flour and cook, whisking constantly, for 2 minutes, until lightly golden but not browned.
  
• Add the stock: Gradually whisk in the turkey stock. It will look lumpy at first, but keep whisking as you add it. Bring to a gentle boil, whisking frequently, then reduce the heat and simmer for 5 to 8 minutes, until smooth and thickened.
  
• Finish: Remove from the heat and whisk in the remaining 1 tablespoon of butter. If any small lumps remain, strain the gravy once more through a fine-mesh sieve. Taste and season with more salt and pepper, if needed. Serve right away, or store it using the make-ahead steps below.
  

Make-Ahead Instructions

• Store: Let the gravy cool, then transfer it to an airtight container. Refrigerate for up to 3 days, or freeze for up to 3 months.
• Reheat: Warm the gravy in a saucepan over medium-low heat, whisking frequently. If it's too thick, gradually whisk in more broth until it reaches the consistency you like.

Adding Turkey Drippings (Optional)

• Stir in drippings: Once your Thanksgiving turkey is roasted, you can stir some of the strained pan drippings into the prepared gravy. Since the drippings maybe salty, add them gradually and taste as you go. If the gravy becomes too thin, simmer it uncovered for a few minutes.