Press whole cloves into the ham so they are evenly distributed. You may score the ham for easier insertion if you wish. Place the ham in a slow cooker. Pour in apple cider until only about 5cm of ham is above the surface. Pack the brown sugar on top of the ham, pressing into the cloves. This will get washed away in the next step but any that stays on is a bonus.
Pour the maple syrup over the ham. Season the apple cider with cinnamon, nutmeg, ginger, ground cloves and vanilla. Add the orange peel to the pot. Fill the slow cooker as full as you can with apple cider without going over the fill line. Cover and set to Low. Cook for 8 to 10 hours.