To cook gammon in a slow cooker, place the gammon joint in the slow cooker with a small amount of liquid such as water, apple cider, or cola to mostly cover it. Add aromatics or spices like bay leaves, peppercorns, cinnamon, or onions for flavor. Cook on low for 6 to 8 hours or on high for about 4 to 5 hours, depending on the size of the gammon. Use a meat thermometer to ensure the internal temperature reaches at least 68-71°C (155-160°F) to confirm it is thoroughly cooked. After slow cooking, remove the gammon and let it cool slightly. For a glazed finish, remove the skin, score the fat in a diamond pattern, brush a glaze made from ingredients like honey, mustard, brown sugar, or balsamic and orange juice, and caramelize the glaze in a preheated oven at about 200°C (400°F) for 10-25 minutes. Let the gammon rest before slicing and serving. Variations include cooking gammon in cola with spices for a sweet flavor or using a balsamic and orange glaze. The slow cooker method makes the gammon tender and flavorful with minimal hands-on time.