Preheat your oven to 350°F (180°C). Drizzle olive oil over the tops of the garlic heads, wrap each in foil, and place them on a baking sheet. Roast for 60-90 minutes until golden and soft.

Heat a tablespoon of olive oil in a large saucepan over medium heat. Add the diced onion and sauté for about 5-7 minutes until translucent.

Once the garlic is roasted, unwrap and let it cool. Squeeze the caramelized garlic cloves into the onion mixture and cook for about 1 minute.

Pour in the broth, white beans, and fresh rosemary. Bring to a gentle boil, then reduce heat and let simmer for 5 minutes.

Using an immersion blender, puree the soup until smooth and velvety. If using a standard blender, blend in batches until creamy.

Stir in grated parmesan cheese if using, then squeeze in fresh lemon juice. Season with salt and pepper to taste.

Ladle the soup into bowls and enjoy hot, paired with crispy bread or toppings of choice.