Drizzle two tablespoons of the olive oil in a large saucepan and preheat your oven to 350°F. Place 30 peeled garlic cloves in a small oven-proof casserole dish, drizzled with remaining olive oil. Cover with foil and roast for 35 to 40 minutes until soft and golden brown.

While the garlic roasts, chop the remaining 10 garlic cloves and add them to the saucepan along with the chopped onion and potato. Sauté over medium heat for about 5 minutes until the vegetables soften and begin to brown.

Pour in the chicken broth, add dried thyme, and season with salt and pepper. Bring to a boil and then reduce the heat to simmer until the potatoes are incredibly tender, about 15 to 20 minutes.

Once the garlic has finished roasting, allow it to cool slightly. Scoop the roasted garlic from the oil and add it to the soup. Reserve the garlic oil for later.

Allow the soup to cool to room temperature before pureeing it in batches until thick and smooth. Return the pureed soup to the saucepan.

Reheat the soup over low heat and stir in the tablespoon of lemon juice. Taste and adjust seasoning as desired.

Ladle the warm soup into bowls, garnishing with fresh herbs, a drizzle of reserved garlic oil, or a sprinkle of grated cheese if desired.