Prepare the Apples: Peel, core, and slice the apples. for best results use a variety of apples for the best flavor. If you have an apple corer/peeler, it will save you time.
Cook the Apples: Place the apples in a large pot or slow cooker. Cook over medium heat until the apples are soft and breaking apart, about 30-40 minutes on the stove or 4-6 hours on low in a slow cooker.
Blend the Apples: Once the apples are tender, use a food mill or an immersion blender to puree them until smooth. If you don’t have an immersion blender, you can transfer the apples in batches to a regular blender or food processor. Be careful when blending hot liquids.
Add Spices and Sugars: In a separate bowl, combine the sugars, cinnamon, nutmeg, cloves, vanilla, and salt. Mix well, then add this mixture to the apples and stir to combine.
Cook the Apple Butter: Continue cooking the mixture over low heat, stirring frequently to prevent burning. Cook for 1-2 hours, or until the apple butter has thickened and darkened in color. If using a slow cooker, leave it on low and let it cook for 6-8 hours, stirring occasionally. The apple butter is ready when it reaches a thick, spreadable consistency.
Test for Consistency: To check if the apple butter is ready, place a small spoonful on a plate and let it cool for a minute. Run your finger through the apple butter; it should hold its shape and not run.
Add Lemon Juice (Optional): Stir in lemon juice if you want to help with preservation, especially if you plan to can the apple butter.
Cool and Store: Allow the jars to cool completely before storing them in a cool, dark place. Once opened, apple butter can be kept in the refrigerator for several weeks.