Digestive biscuits can be used instead of graham cracker crumbs in the same amount. If you choose this substitute, reduce or skip the added sugar in the crust since digestive biscuits are already sweet. For the best texture and a properly set filling, always use full-fat brick-style cream cheese rather than spreadable tub cream cheese. Store the cheesecake covered in the refrigerator for up to 3 days, or wrap it tightly and freeze for up to 1 month.