Brown the butter: In a medium saucepan over medium-low heat, melt the butter. Continue cooking, swirling the pan occasionally, for 4 to 6 minutes until the foam subsides, the butter turns a deep amber color, and it smells nutty and toasty. Watch carefully — it can go from browned to burnt quickly. Remove from heat for 30 seconds.

Make the roux: Return the saucepan to medium heat. Add the flour all at once and whisk vigorously to combine with the browned butter. Cook the roux, stirring constantly with a wooden spoon or whisk, for 2 to 3 minutes until it turns pale golden and smells slightly nutty.

Deglaze: If using sherry or white wine, pour it in now and whisk vigorously — it will sizzle. Cook for 1 minute, stirring, until the alcohol cooks off.

Add the drippings: Slowly pour in the turkey drippings in a thin, steady stream, whisking constantly to prevent lumps. Whisk until fully incorporated and smooth.

Add the stock: Continue whisking in the turkey or chicken stock in a slow, steady stream until everything is combined and smooth.

Simmer and season: Add the thyme sprigs, bay leaf, Worcestershire sauce (if using), salt, and pepper. Bring to a gentle simmer over medium heat, stirring frequently, and cook for 8 to 10 minutes until the gravy has thickened to a silky, pourable consistency that coats the back of a spoon.

Strain and serve: Remove the thyme sprigs and bay leaf. Pour the gravy through a fine-mesh strainer into a warmed gravy boat or serving pitcher. Taste and adjust salt and pepper as needed. Serve immediately, or keep warm over the lowest heat setting, stirring occasionally.