While your roast beef rests, consider making gravy using the leftover beef broth and drippings. First, strain the drippings and bring them to a boil in a saucepan. Then, make a cornstarch slurry using ¼ cup cold water and three tablespoons of cornstarch. Add the slurry to the drippings and whisk the mixture. Allow it to boil for 1-2 minutes, then reduce the heat to low to let it simmer for another several minutes as it thickens. Season with salt, pepper, garlic powder, and a splash of Worcestershire sauce.