Combine the water, chopped apples, sugar, and spices in your slow cooker. Cover and put on low.
Cook for 4 hours.
Open and smash apples to remove any chunks. Replace lid and cook another hour.
Remove the lid and, if desired, remove spices and puree with an immersion blender.
Return spices to the pot and turn crock pot up to high. Cook, uncovered 1 hour or until thickened, dark, and smooth.*
If adding vanilla, add it in the final 10 minutes, and remove the spices.
Canning Instructions, Optional
If canning your apple butter, place the canning pot full of water over high heat. Bring to a rolling boil.
In the last ten minutes of your apple butter cook time, immerse clean canning jars into the water for a few minutes.
Use jar clamps to remove the jars and turn them upside down on a clean dish towel to dry.
When your apple butter is done, flip the jars right side up and fill with apple butter, leaving 1/4 inch of space between it and the rim.
Wipe the rims clean and dry, then place on new seals and bands. Use hand protection and tighten bands as much as possible.
Submerge in boiling canner for 10 minutes, then remove and let sit on counter until cool and has sealed, (the seal doesn't move when touched),
Notes
*To test if you apple butter is set enough, place a spoon in the freezer for a few minutes. Then remove and drip on some apple butter. If the apple butter congeals and sticks to the spoon, it's ready.