Place finely chopped apples in a 6-quart slow cooker. Combine sugar, cinnamon, cloves, and salt in a medium bowl. Pour over the apples and mix well.

Cover and cook on High for 1 hour. Reduce heat to Low and cook, stirring occasionally, for 9–11 hours, until the mixture is thick and dark brown.

Uncover and cook on Low for 1 additional hour. Whisk until smooth, or blend with an immersion blender if desired.

Cool and transfer to clean, covered containers. Refrigerate for up to 2 weeks or freeze for up to 3 months.