For the ham hocks, rinse the ham hocks with fresh water. Place them into a large pan and cover with water.
Add the onion, carrots, bay leaf and white peppercorns and bring the mixture to the boil. Reduce the heat to a simmer and simmer for two to three hours, or until the meat is tender and falling from the bone. Set aside to cool.
Preheat the oven to 200C/400C/Gas 6.
Trim the outer layer of fat from the cooled ham hocks, then make criss-cross patterns in the remaining soft fat on the hocks using a sharp knife.
In a bowl, mix together the honey and mustard until well combined.
Line a large roasting tray with aluminium foil. Fill the tray with the ham hocks and the boiled vegetables. Spread the honey and mustard mixture all over the ham hocks. Roast in the oven for 25-30 minutes, basting regularly with the juices that collect in the roasting tray, or until the ham is tender and completely cooked through.
Meanwhile, for the colcannon, heat the oil in a frying pan over a medium heat. Add the onion and fry for 8-10 minutes, or until softened and golden-brown.
In a large bowl, mix together the mashed potato, butter, cream, blanched cabbage and mustard until well combined and season, to taste, with salt and freshly ground black pepper.
Transfer the potato mixture to the frying pan with the onions in and press down to form a large potato 'cake'. Fry for 4-5 minutes, or until crisp and golden-brown on one side. Turn over, using a plate if necessary to help you, and fry on the other side for a further 4-5 minutes, or until crisp and golden-brown on both sides.
For the cheese sauce, in a separate pan, bring the double cream, garlic clove and bay leaf to the boil. Reduce the heat to a simmer, then simmer the mixture until the volume of liquid has reduced by a third, about 10-15 minutes. Strain the mixture through a fine sieve and discard the garlic clove and bay leaf. Return the liquid to the pan.
Add the grated cheese and stir until completely melted.
To serve, carve the ham into thick slices and divide equally among eight serving plates. Place a spoonful of the colcannon alongside each. Drizzle over the cheese sauce.
