Normally I grind hard cheeses such as Pecorino and Parmesan in a food processor rather than grate them for consistency in measuring. To scald milk, heat it to just below the boiling point, when bubbles start to form around the perimeter. Don’t allow it to boil. To make these ahead, bake the puffs and allow them to cool, then freeze in a sealed bag. Place on a sheet pan lined with parchment paper and reheat at 375˚ F for 10 minutes.