In a large bowl mix together the sugar, cinnamon, cloves and salt. Pour it over the diced apples, add the honey and mix well.
Place the apple mixture in a slow cooker and cook it, covered, on high, for 45 minutes. Taste the mixture and add more sugar or honey, if necessary. Recover it, set the crock pot temperature to low, and cook it overnight for 9-11 hours. (It will darken in color.)
In the morning, remove the crock pot lid and cook it in low for an hour, which thickens it.
Once cool, the apple butter can be frozen and served later, defrosted.