Core and chop the apples into small pieces (about 1/4 inch).
In a large slow cooker, add the chopped apples. In a separate bowl, mix together brown sugar, granulated sugar, cinnamon, salt, and cloves. Sprinkle this mixture over the apples and stir to combine.
Cover the slow cooker and set it to low heat. Cook the apple mixture for 9-10 hours.
Use an immersion blender to purée the apples until smooth. Stir in the vanilla extract.
Continue cooking on low heat for an additional 2 hours, uncovered. Stir the mixture occasionally.
Allow the apple butter to cool and then store it in airtight containers in the refrigerator for up to 2 weeks.