01 -
In a large pot, heat olive oil and butter over medium heat. Sauté the onion until softened, about 5 minutes.
02 -
Add the garlic cloves to the pot and cook for 2-3 minutes, stirring frequently to avoid burning.
03 -
Pour in the broth and add the thyme sprigs and bay leaves. Bring to a boil, then reduce the heat and simmer for 30 minutes.
04 -
Remove the thyme sprigs and bay leaves from the pot. Season with salt and pepper to taste.
05 -
In a small bowl, whisk together the egg yolks and Parmesan cheese. Gradually temper the egg mixture by whisking in a ladle of hot soup.
06 -
Slowly add the tempered egg mixture back into the soup, whisking constantly. Simmer for 5 minutes, allowing the soup to thicken slightly.
07 -
Ladle the soup into bowls and serve hot with crusty bread. Garnish with fresh parsley, if desired.