In a large pot or slow cooker, add the apples and apple cider (or water). Cover and cook on low heat (or slow cooker on low) for about 6–8 hours, stirring occasionally, until the apples are soft and broken down.

Use an immersion blender (or transfer to a blender in batches) to puree the mixture until smooth.

Stir in sugar, brown sugar, cinnamon, cloves, salt, and any optional spices. Continue to cook uncovered on low, stirring frequently to prevent sticking, for another 1–2 hours, or until it thickens to a spreadable consistency.

Once thick and dark brown, remove from heat. Stir in vanilla extract if using.

Let cool, then transfer to clean jars. Refrigerate for up to 3 weeks, or freeze for longer storage.