Peel, core, and chop the apples: Start by peeling and coring your apples. Chop them into small chunks to ensure even cooking.
Add apples to the slow cooker: Place the chopped apples in your slow cooker.
Add sugars and spices: Add the granulated sugar, brown sugar, cinnamon, cloves, nutmeg, and salt to the apples. Stir to mix everything evenly.
Cook on low: Set your slow cooker to low and cook for 10 hours, stirring occasionally. Your house will start to smell amazing as the apples break down and the flavors meld together.
Blend until smooth: After 10 hours, use an immersion blender directly in the slow cooker to blend the apple mixture until smooth.
If you don’t have an immersion blender, carefully transfer the mixture to a regular blender in batches and blend until smooth, then return to the slow cooker.
Cook for 1-2 more hours: After blending, continue cooking on low for an additional 1-2 hours with the lid slightly ajar to allow steam to escape and the mixture to thicken.
Add vanilla extract: Stir in the vanilla extract during the last hour of cooking.
Cool and store: Once your apple butter has reached the desired consistency, let it cool before transferring it to sterilized jars. Store in the refrigerator for up to 2 weeks or freeze for longer storage.