In a large pot, melt the butter over medium heat. Add the onions and cook until they are translucent, about 5 minutes. Stir in the garlic and red pepper flakes; cook for another 10-20 seconds until aromatic.
Add the broth, chopped potatoes, and beans. Bring to a gentle simmer and cook for 10-15 minutes, or until the potatoes are tender.
Use an immersion blender to puree about half of the soup (or transfer to a blender in batches). This will give the soup a creamy texture.
Stir in the chopped kale and simmer for another 5 minutes until the kale has softened. Add salt and pepper to taste.
Ladle into bowls and Enjoy!
Notes
*I use this bouillon for this soup -Better Than Bouillon No Chicken BaseStorageStore leftovers in an airtight container in the refrigerator for up to 4 days. This soup also freezes well for up to 3 months - just thaw in the refrigerator overnight and reheat on the stove.