In a saucepan, over medium-high heat, bring the chicken stock to a boil.
In a bowl, whisk the eggs, and add the Parmigiano, semolina, nutmeg and lemon zest.
Add the egg mixture, a little at a time, to the boiling stock, whisking constantly. After all the egg mixture is added, lower the heat and cook 1 minute.
Adjust the seasoning with salt and pepper.
Ladle into bowls and garnish each with chopped parsley and a drizzle of olive oil. Add sprinkle of red pepper flakes if desired.