To cook a gammon joint in a slow cooker:

• Place the gammon joint in the slow cooker along with aromatics like onion, peppercorns, bay leaves, and spices if desired.
• Add enough liquid to mostly cover the gammon, such as water, apple cider, cola, or stock.
• Cook on low for 6 to 8 hours or on high for 4 to 5 hours, depending on the size of the joint and slow cooker.
• Check the internal temperature with a meat thermometer; it should reach around 68-71°C (155-160°F) to be fully cooked.
• Once cooked, remove the gammon and let it rest. Optionally, remove the skin, score the fat, and glaze it (e.g., with honey, mustard, brown sugar, or a balsamic-orange glaze).
• For a glazed finish, place the gammon under a hot oven grill or in the oven at about 200°C (400°F) for 10-25 minutes until caramelized.
• Let it rest before slicing and serving.

Various recipes include additional flavor elements like cinnamon, ginger, cloves, or glazes made with ingredients such as honey, mustard, brown sugar, or balsamic vinegar and orange juice to enhance the taste.