Prep Apples & Slow Cooker: Peel, core, and slice 5.5 lbs of apples. Place all apple slices directly into a 6-quart slow cooker crockpot.

Toss with Spiced Sugars: In a medium bowl, whisk together dark brown sugar, granulated sugar, ground cinnamon, nutmeg, cloves, allspice, and salt. Pour over apples and toss to distribute.

Slow Cook on Low (10 Hours): Cover with the lid and cook on LOW heat for 10 hours (or HIGH for 5 hours), stirring once or twice if convenient. The apples will turn soft, dark amber, and release aromatic juices.

Purée Silky Smooth: Uncover slow cooker. Use an immersion hand blender directly in the pot and purée until the apples transform into a completely smooth, velvety sauce without any lumps.

Thicken Uncovered: Leave lid slightly ajar or completely off. Continue cooking on LOW for another 1 to 2 hours, stirring occasionally, until the apple butter thickens into a rich, spreadable paste that holds its shape on a spoon.

Stir in Vanilla & Cool: Turn off heat and stir in vanilla extract. Ladle warm spiced apple butter into clean mason jars. Cool completely before sealing and storing!