Heat the oil in a large skillet or Dutch over. Add the onion and cook over medium high heat, stirring occasionally. Once the onion starts to soften a bit, after 3 or 4 minutes, add the slivered garlic. Cook for a minute more, then add the greens and any herbs. Season with ½ teaspoon salt.
As the greens cook down, turn them in the pan to bring the ones on top closer to the heat. Once they've all collapsed, add ½ cup water or bean broth, lower the heat and cook. Partially covered, until tender. Depending on the greens as long as 20. Just make sure there is some liquid in the pan for sauce. When the greens are done, add the beans, heat them through, then taste for salt and season with pepper.
Toast the bread and rub it with the halved garlic. Arrange on plates and spoon on the greens and beans. Drizzle with olive oil. Garnish with the cheese, if using, and serve.