Place the chicken broth and drippings (if using) in a pan and bring to a boil.
Place the corn starch (or other thickener) in a mug and add ¼ cup of the hot broth. Whisk well with a fork.
Add the starch/broth mixture to the pan. Add the garlic powder, onion powder, and salt and pepper. Cook over medium heat while whisking to remove any lumps. The gravy should thicken pretty quickly. If it is too thick, add some more broth.
Season with more salt and pepper if desired before serving.
Notes
Store leftover gravy in the refrigerator. It should stay fresh for about 4 days.You can also freeze this gravy - store in a freezer safe container. It should stay fresh in the freezer for about 3 months.You can double or triple this recipe if you need to feed a bigger crowd.