Beat the grated parmesan and soft cheese or ricotta in a bowl until well blended and creamy; add a dash of milk to loosen the mixture, if you like.
Add white or black pepper, salt and nutmeg to taste, and mix again.
Split the focaccia or rolls and spread both sides thinly with the parmesan cream.
Lay two slices of mortadella on one half of the bread, top with the other half of bread and repeat with the remaining bread, cream and sausage.
