From Bon Appétit, March 2013
1/2 1-pound loaf sourdough bread, torn into 2″ pieces (about 6 cups)
1 bunch collard greens, center ribs and stems removed
1 bunch Tuscan or other kale, center ribs and stems removed
1/2 cup olive oil, divided, plus more for serving
2 medium carrots, peeled, finely chopped
2 celery stalks, finely chopped
1 leek, white and pale-green parts only, chopped
4 garlic cloves, chopped
1/2 teaspoons crushed red pepper flakes
1 28-ounce can whole peeled tomatoes, drained
8 cups low-sodium vegetable broth
3 15-ounce cans cannellini (white kidney) beans, rinsed
4 sprigs thyme
1 sprig marjoram or oregano
1 bay leaf
Freshly ground black pepper
Shaved Parmesan (for serving)
Scatter bread on a rimmed baking sheet in a single layer. Let stand at room temperature to slightly dry out, about 2 hours.
Working in batches, cook collards and kale separately in a large pot of boiling salted water until slightly softened, about 3 minutes per batch. Rinse to cool. Squeeze out excess water; roughly chop. Set aside.
Heat 1/4 cup oil in a large heavy pot over medium heat. Add carrots, celery, and leek; stir often until softened, 8-10 minutes.
Add garlic and red pepper flakes. Cook, stirring until fragrant, about 1 minute. Add tomatoes, crushing with your hands as you add them. Cook, stirring frequently, until liquid is evaporated and tomatoes begin to stick to the bottom of the pot, 10-15 minutes.
Add broth, beans, thyme, marjoram, bay leaf, and reserved greens; season with salt and pepper. Bring to a boil, reduce heat, and simmer until flavors meld and soup thickens slightly, 40-50 minutes. DO AHEAD: Soup can be made 2 days ahead. Let cool slightly; chill until cold. Cover and keep chilled. Reheat before continuing. Store bread airtight at room temperature.
Just before serving, gently stir bread and 1/4 cup oil into soup. Divide among bowls, top with Parmesan, and drizzle with oil.