This fantastic soup is inspired by a Martha Rose Shulman recipe, from her New York Times “Recipes for Health” column, where cabbage is cooked in a combination of broth and milk. My adaptation tastes sophisticated even without any dairy (thanks to cabbage, that chameleon, showing off a whole new side of itself when cooked), but the Gruyère makes the soup absolutely elegant. I’ve added white beans for heft and creaminess. Taste carefully for seasoning toward the end—I find that after adding the cheese I need to add a bit more salt to bring the flavors into balance.
Warm the olive oil in a soup pot over medium heat, then stir in the onions and garlic, followed by the cabbage and salt. Cook for about 5 minutes, until just starting to soften, then add the beans and broth.
Bring to a simmer, then cover and cook for 30 minutes, or until the vegetables are tender and the broth is flavorful.
Remove from the heat and add the cheese a handful at a time, stirring until it melts into the broth.
Taste and season with additional salt, as needed (depending on the saltiness of your vegetable stock or bouillon, it may need quite a bit of salt, as the beans really soak it up), and a few grinds of pepper.
Serve hot, topped with breadcrumbs or croutons, if desired.