How to Make It
Heat butter in a pot over medium-high. Add onion and cook, stirring occasionally, until tender, about 4 minutes. Add garlic and cook, stirring constantly, 1 minute. Stir in broth, salt, pepper, and 1 can of beans. Bring to a boil; reduce heat to medium-low and simmer 20 minutes.
Meanwhile, puree remaining can of beans in a food processor until smooth. Add to soup.
Stir in spinach and cook until wilted, 1 minute. To serve, top soup with cherry tomatoes and Swiss cheese.