For the Piedmont style fondue, grate the cheese.
Bring the milk and butter to the boil, add the grated cheese and melt over low heat, stirring constantly.
Season with pepper, nutmeg, sugar and salt and fold in the finely chopped lemon balm.
Stir the cornstarch with the water until smooth and thicken the fondue with it.
Refine the fondue Piedmont style with grappa.