To begin place your prepared apples and the water in a large, non-reactive pot.
Bring the apples up to a gentle boil, then reduce the heat and simmer until the apples are tender, and you can mash them with the back of a large spoon.
Remove the apples from the heat, and use an immersion blender to puree the apples. I like to leave random little bits of apples in mine. If you do not have an immersion blender, this can be done with a standard blender. Simply work in batches.
Add in the sugar, brown sugar, cinnamon, nutmeg and salt. Bring the mixture up to a gentle boil, then reduce the heat to a low simmer. Place the lid on the pot, but leave it cracked for the steam to escape. Stir the apple butter often.Cook until the apple butter is thickened. This can take 3 hours or more, depending upon how much moisture there is in your apples. See the recipe post above for a couple other "cooking down" options.
When your apple butter is done, prepare all of your canning supplies, and heat the jars. Jars should be washed and inspected for chips or other faults. You can use pints or half pints. I usually do a combination of the two.
Ladle the hot caramel apple butter into hot jars, leaving a 1/2 inch head space.
Remove any bubbles with a bubble wand, then wipe the rim of the jars very well with a damp cloth dipped in white vinegar.
Place a lid and ring on the jar and place the jar in the hot water bath or steam canner. Do this with all of the jars.
Process the jars for 15 minutes. (See the note about adjusting time for elevation in the article above. Processing times for canning recipes are always give for under 1000 ft elevation. You must make adjustments if you live at a higher environment.)
After the jars have processed, turn off the heat. If using a hot water bath canner, remove the lid of the canner, and let the jars rest for 5 minutes. If using a steam canner, leave the lid on (heat off) for 5 minutes, then take it off.
Transfer the jars to a lined surface in a draft-free location and let them sit for 12-24 hours. You can cover your counter with folded kitchen towels, or use a cooling rack.
Remove the rings, test the seals, wash and label the jars. Store them away in the pantry.