Slice the celeriac and potatoes raw and put in a large bowl. Sweat the onions in a little oil and season with pepper, cumin, 4 bay leaves and 2 sprigs of thyme.
Add the sweated onions into the celeriac and potato whilst still hot along with the garlic so all the flavours start to mingle. Bring the stock to the boil and cook the cabbage for about 4-5 minutes until tender. Remove and drain but keep warm.
Add the gammon slices into the hot stock and cook for about 5 minutes, then remove and keep warm. Start to construct the dish by placing a layer of the celeriac/onion etc in the bottom of the pan.
Now alternate layers of cabbage, gammon and cheese and potatoes etc with seasoning until all the mixtures are used and the gammon is totally covered.
Pour the remaining stock over the dish just to the top of the layers. Top with more cheese and remaining herbs.
Cover with aluminium foil and cook in the preheated oven for approximately 40 minutes at 140 - 150c.