Peel, core and slice the apples and add them into the crock pot. Fill it all the way up to the top because the apples will cook down a lot. Add in the water and the cinnamon if you are using it. Cover and put the crock pot on low for about 6 hours.
Once the apples are very soft mash them up with a spoon or potato masher. You can also blend it if you like super smooth apple sauce. Put the applesauce into jars or sealed containers. Store the extra in the freezer until you ready to eat it.