In a large pot, over medium heat, bring the tomatoes and their liquid to a simmer. Cook for 2 minutes.
Add the broth, cannellini, and kidney beans (if using) and bring to a simmer. Add the green beans and cook until tender, about 3 minutes.
Add ½ teaspoon salt, ¼ teaspoon pepper, and spinach and stir until wilted.
Ladle the soup into bowls and sprinkle with the Parmesan. Serve with the bread.