Peel, core and cut the apples into eight pieces each.
Add the apples, cinnamon, lemon juice and sugar to a slow cooker, stirring until the apples are thoroughly coated.
Cook the apples on HIGH for 4 to 5 hours. Once the apples are very tender, mash them with a fork until your reach your desired consistency. (For extra-smooth applesauce, purée the cooked apples in batches in a blender.) Taste and season with additional cinnamon as desired.
Serve immediately or store in an air-tight container in the fridge.