Stir the grated Parmesan into the beaten eggs (you may optionally add a pinch of nutmeg and some lemon zest).
Heat the broth until simmering. Turn off the heat.
Pour the egg-cheese mixture into the broth. After a few seconds, stir lightly.
Taste and season with salt and pepper. Take it easy on the salt because Parmesan is salty and some of that saltiness will find its way into the broth.
Optionally garnish with snipped parsley and serve.