"Delicious slow cooker apple butter with the flavor of Christmas. It comes from the spices of German gingerbread, called lebkuchen. Not a family recipe, but it will be in 2 more generations. Keeps for 7 to 10 days when opened. Refrigerate after opening."
Combine 4 cups apples and 1/2 cup water in a high-powered blender; puree until smooth. Pour into a large slow cooker. Repeat with remaining apples and water.
Stir honey, cocoa powder, cinnamon, cardamom, and cloves into the apple puree in the slow cooker.
Cook on High, stirring occasionally, until thickened and brown, about 10 hours.
Immerse six 1-pint jars in simmering water for 5 minutes. Wash lids and rings in warm soapy water.
Pack apple butter into hot jars, filling to within 1/4 inch of the top. Run a clean knife or thin spatula around the insides of the jars after they have been filled to remove any air bubbles. Wipe rims with a moist paper towel to remove any food residue. Top with lids and screw on rings.
Place a rack in the bottom of a large stockpot and fill halfway with water. Bring to a boil and lower jars 2 inches apart into the boiling water using a holder. Pour in more boiling water to cover jars by at least 1 inch. Bring the water to a rolling boil, cover the pot, and process for 10 minutes.
Remove the jars from the stockpot and place onto a cloth-covered or wood surface, several inches apart, for 24 hours. Press the center of each lid with a finger to ensure the seal is tight and the lid does not move up or down. Store in a cool, dark area.