Preheat your oven to 400°F (200°C). Slice off the top of a whole head of garlic and drizzle it with olive oil. Wrap it tightly in aluminum foil and place it directly on the oven rack. Roast for 35–40 minutes until the garlic is soft and caramelized.

In a large pot, heat a splash of olive oil over medium heat. Add the chopped onion and celery, sautéing for 5–7 minutes until they're softened and fragrant.

Once the garlic is roasted, carefully squeeze the sweet cloves into the pot with the sautéed onions and celery. Toss in the chopped fresh rosemary and stir briefly.

Add the drained cannellini beans, low-sodium vegetable broth, bay leaf, salt, and pepper to the pot. Stir together and bring to a gentle boil. Reduce the heat and let it simmer uncovered for about 20 minutes.

Remove the bay leaf from the pot. Use an immersion blender to puree the soup until it reaches your desired consistency.

Stir in a splash of lemon juice to balance the flavors. Taste and adjust seasoning, then serve hot, garnished with croutons, fresh parsley, or a drizzle of olive oil.