Preheat the oven to 180°C.
Dry fry pancetta for 2-3 minutes until golden. Drain on kitchen paper.
Layer the potatoes, celeriac, onion, garlic, walnuts, pancetta and 150g Gorgonzola in a large heavyweight baking dish.
Mix together the cream and milk and pour over the potato mixture.
Dot over the remaining Gorgonzola and sprinkle a little nutmeg.
Bake in the oven for one hour or until cooked through and golden brown.
Recipe courtesy of Gorgonzola