Heat a large soup pot on high. Add olive oil, onions and garlic. Sauté until onions are soft. Sprinkle salt and pepper. Add rosemary and chile flakes. Cook for several minutes, then add white beans and water. Bring to a simmer, add the tomatoes and simmer gently for 20 minutes.
Remove the stems from the kale, finely chop the leaves and rinse thoroughly under cold water. Add the kale leaves to the soup and cook until wilted.
Garnish with fresh parmesan cheese if desired!
*Sometimes you might want to add more water depending on how thick the soup is.
Adapted from ReBar ModernFoodCookbook