Preheat your oven to 400°F (200°C). Slice the top off a head of garlic and drizzle it with olive oil. Wrap it snugly in foil, then place it in the oven for 35-40 minutes.

Heat a tablespoon of olive oil in a large pot over medium heat. Add finely chopped onion and celery to the pot, sautéing for 5-7 minutes until they become soft and translucent.

Once your aromatics are ready, squeeze the roasted garlic cloves into the pot, discarding the skins. Add chopped fresh rosemary and stir for 1-2 minutes until the herbs release their fragrant aroma.

Stir in the drained cannellini beans, followed by low-sodium vegetable broth and a bay leaf. Season the mixture with salt and pepper to taste. Bring everything to a boil, then reduce the heat and let it simmer gently for 20 minutes.

Carefully remove the bay leaf from the pot. Using an immersion blender, blend the soup until smooth or to your desired texture.

Off the heat, stir in freshly squeezed lemon juice, adjusting seasoning with additional salt and pepper if needed.