Place a medium saucepan over medium heat and add the butter. Let it melt completely until it begins to foam slightly.

Sprinkle the all-purpose flour over the melted butter. Use a whisk to stir the mixture constantly for 3 to 5 minutes until it turns a pale golden-brown and smells slightly nutty.

Slowly pour in one cup of the turkey stock while whisking vigorously until it thickens into a paste.

Gradually add the remaining stock, one cup at a time, whisking constantly to prevent lumps.

Stir in the onion powder, garlic powder, thyme, and sage, or drop in the fresh herb sprigs whole.

Bring the mixture to a gentle simmer, then reduce the heat to low and cook for about 10 minutes, stirring occasionally.

Season the gravy with salt and black pepper to taste.

Remove any fresh herb sprigs before serving. If the gravy is too thick, whisk in more stock. If it's too thin, simmer for a few more minutes.