These cheesecake bars are the easiest to slice when they are cold. At the very least, they should be completely cool before cutting into them. Use a sharp knife, not serrated. I like to use a large chef's knife. Slice into the bars downwards, then carefully pull the knife out. Wipe the knife off on a hot, damp towel between slices for the neatest cuts. Spraying the knife with a light layer of cooking spray between slicing can also make clean cuts and prevent sticking.