Prepare the Bean Puree: Drain and rinse one can of cannellini beans thoroughly. Place these beans in a blender or food processor along with 1 cup of chicken broth. Blend until smooth and creamy, setting aside for later.
Cook the Bacon and Vegetables: Heat the oil in a large heavy-bottomed pot or Dutch oven over medium heat. Add the chopped bacon and cook until it crisps up and releases flavorful fat. Once the bacon is golden and crispy, add the chopped onion, carrot, and celery. Sauté the vegetables until they soften and become fragrant, about 6 to 7 minutes.
Add Aromatics: Mix in the minced garlic and fresh rosemary, stirring constantly for about 30 seconds until their aroma is released but before the garlic browns.
Combine Beans, Potatoes, and Broth: Pour in the blended bean mixture, the remaining two cans of drained cannellini beans, the diced potatoes, and the rest of the chicken broth. Season with salt and pepper according to your preference. Bring the mixture to a gentle simmer over medium or medium-low heat, uncovered, and cook for 20 to 25 minutes, or until the potatoes are tender and the soup has slightly thickened.
Add Kale and Finish: Stir in the chopped kale and continue to simmer for a few more minutes until the greens are wilted but still vibrant. Taste and adjust seasoning if needed. Just before serving, stir in the fresh parsley.
Serve: Ladle the soup into bowls and optionally garnish with freshly grated Parmesan cheese. Serve hot, ideally with crusty bread for dipping.
