EDIT: Apple butter recipe stolen from Tabitha. I used 15 large Red Delicious apples and pureed in my blender. It yielded 12 six ounce jars.
Here's her recipe:
About 1 peck of apples (different varieties picked from the orchard)
3 cups sugar (I use organic cane sugar)
3 teaspoons cinnamon
Pinch of salt
After we peel, core and cut up the apples, I throw them in my crockpot and mix in the rest of ingredients. Cook on high for 1 hour, then on low for 10-11 hours. If you can remember, take the lid off for the last hour and stir.
Once cooked, carefully spoon into food processor and blend until smooth.
Ladle into canning jars and place upside down to seal or place in water bath.