Heat the olive oil in a large pot over medium heat and add the onion, celery, and garlic. Cook until the vegetables start to soften, 5-7 minutes.
Add the beans, potatoes, rosemary, salt, and pepper and cook with the onion mixture until well blended, 2-3 minutes.
Stir in the vegetable broth, bring to a boil, then reduce the heat and simmer for 20 minutes.
Carefully remove half the soup into a blender and blend until smooth and creamy. Return the blended portion of the soup on top of the soup in the pot. Add the kale and simmer until the kale is tender, about 10 minutes.
Stir in the lemon juice, ladle into bowls and serve with grated parmesan cheese and crushed red pepper, if desired.
Notes
Storage: Kept in an airtight container in the fridge, this soup will keep for up to 5 days! To reheat it, you can do so in a saucepan on the stovetop! You can also use the microwave, but it tends to heat soup less evenly.