In a medium saucepan over medium heat, melt the unsalted butter (or meat drippings, if using).
Whisk in the prepared dry gravy mix and cook, whisking constantly, for 1 to 2 minutes to form a smooth roux.
Slowly pour in the beef broth while continuing to whisk, breaking up any lumps as the mixture comes together.
Bring the mixture to a gentle simmer. Cook, whisking occasionally, until the gravy thickens enough to coat the back of a spoon, about 5 minutes.
Remove from the heat and let the gravy rest for a few minutes. It will continue to thicken slightly as it cools.