In a large pot, heat 2 tablespoons of olive oil and 2 tablespoons of butter over medium heat. Add the chopped onion and sauté for about 5 minutes until translucent.

Add 10 peeled garlic cloves to the pot, stirring them into the onion. Cook for 2–3 minutes until fragrant, being careful not to burn the garlic.

Pour in 4 cups of chicken or vegetable broth, stir well, add fresh thyme and a bay leaf, bring to a boil, then reduce to low and simmer for 30 minutes.

Remove thyme and bay leaf from soup, season with salt and pepper. In a bowl, whisk together 2 egg yolks and ½ cup of grated Parmesan cheese.

Tempering the egg mixture, gradually whisk in a ladle of the hot soup into the bowl to combine.

Slowly whisk the tempered mixture back into the pot and let it simmer for another 5 minutes, stirring gently until the soup thickens.

Ladle the soup into bowls, garnish with fresh parsley, and serve with crusty bread.