Whisk the Eggs Together: Beat the egg yolks and, if using, Parmesan cheese in a medium basin. Put aside.
Gently Whisk the Eggs: Take the soup pot off the stove. To prevent the eggs from curdling, slowly pour in half a cup of boiling soup while whisking frequently. Use an additional ladle of hot soup and repeat the procedure.
Mix in the Egg Whites: Return the tempered egg mixture to the soup pot and whisk constantly while pouring. Put the soup back on the stove and let it simmer for two or three minutes, stirring occasionally, until it thickens a little. Make sure it doesn't boil.
Place the order: Stem the thyme and discard the bay leaf. Spoon the soup into individual bowls and garnish with a toasted bread piece per serve. Toss in some fresh thyme leaves for garnish, if you want.
Ten minutes for preparation | Thirty minutes for cooking
Four servings
