Absolutely! And those biscuits, too. I like to pour any leftover gravy into a gallon-size food storage bag and seal it using water displacement (dip the bag in a large bowl of water up to the zipper, then seal). After sealing you can lay the bag flat in the freezer and the gravy freezes in a space-saving shape. To freeze biscuits, seal them the same way in an airtight food storage bag or container.