1 bunch kale or collard greens
1 tablespoon olive oil
8 ounces kielbasa or fresh Italian sausage (mild or spicy), thinly sliced crosswise
1 large leek (white and light green part only) or 1 bunch green onions, sliced
1 (15-ounce) can white beans, such as cannellini or navy beans, rinsed and drained
3 cups reduced-sodium chicken broth
1/2 teaspoon coarse salt
Freshly ground black pepper
1 to 2 ounces freshly grated Parmigiano Reggiano cheese
Rinse kale, shake dry, and cut out and discard tough center stems. Roll leaves lengthwise into a tight tube and cut crosswise into 1⁄4-inch strips. Set aside.
Heat oil in large, heavy saucepan over medium heat. Add kielbasa and cook until browned, about 5 minutes.
Add leeks and cook over medium heat about 3 minutes. Add kale and cook until wilted, about 3 minutes.
Stir in beans and chicken broth. Bring to a boil, then reduce heat and simmer until kale is tender, 10 to 15 minutes. Add salt and pepper.
Ladle soup into bowls. Grate cheese on top.