Prepare Apples:
Peel, core, and slice apples into even pieces.
Combine Ingredients:
Place apples in a slow cooker. Add granulated sugar, brown sugar, cinnamon, cloves, nutmeg, and salt. Stir to coat apples evenly.
Slow Cook:
Cover and cook on LOW for 10 hours, stirring occasionally, until apples are very soft and dark brown.
Blend:
Use an immersion blender to puree until smooth or transfer to a blender in batches.
Final Cooking:
Stir in vanilla extract. Continue cooking uncovered on LOW for 1–2 more hours, or until thickened to your liking.
Cool & Store:
Let apple butter cool completely, then store in airtight containers or jars.