Heat 2 tablespoons of olive oil and 1 tablespoon of butter in a large pot over medium heat until melted. Add 1 chopped onion and sauté for about 5 minutes until soft.

Add 10 peeled and chopped garlic cloves to the pot and cook for an additional 2-3 minutes, stirring constantly.

Pour in 4 cups of broth, 2 sprigs of fresh thyme, and 2 bay leaves. Bring to a boil, then simmer for 30 minutes.

Remove the thyme sprigs and bay leaves. Season with salt and pepper to taste.

In a mixing bowl, whisk together 3 egg yolks and 1/2 cup of grated Parmesan. Slowly add hot soup to temper the egg yolks.

Stir the tempered egg mixture back into the pot and simmer for an additional 5 minutes.

Serve immediately in bowls with crusty bread and garnish with parsley if desired.