Make Ahead - Gravy can be made up to 3 days ahead. Transfer to a container and cover with plastic wrap, pressing down gently so the plastic is completely touching the surface of the gravy. (This tight covering will prevent a skin from forming on the gravy.) Refrigerate. To reheat the gravy, remove the plastic covering and transfer to a saucepan. Warm over medium heat, whisking frequently. If the gravy is too thick after reheating, add some water or stock about 1 Tablespoon at a time to thin.