Place the apple slices in a large bowl. Add the brown sugar, granulated sugar, cinnamon, nutmeg, cloves, and salt. Stir until well combined.
Place the apple slices in a large slow cooker.
Cover and cook on high 5 hours, or low 10 hours, stirring occasionally, until the apples are tender and dark brown.
Remove the lid and stir in the vanilla extract. Puree with an immersion blender until smooth.
Cook on high for an additional 1.5 to 2 hours, stirring occasionally, so the mixture can thicken.
Spoon into jars or containers. Let cool and then cover and refrigerate for up to 1 month.
Spread on bread, biscuits, or muffins, stir into yogurt or oatmeal, or top your pancakes, waffles, and French toast with it! It also makes a great gift!