Italian Vegetable Stew

Ingredients

• 1/2 1-pound loaf sourdough bread, torn into 2-inch pieces (about 6 cups)
• 1 bunch collard greens, center ribs and stems removed
• 1 bunch tuscan or other kale, center ribs and stems removed
• kosher salt
• 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 teaspoon 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)