Classic Tuscan Ribollita (Hearty Bread and Bean Soup)

Ingredients

• 3 tablespoons extra virgin olive oil, plus more for serving
• 1 medium yellow onion, finely chopped
• 2 medium carrots, diced
• 2 celery stalks, diced
• 4 garlic cloves, minced
• 2 tablespoons tomato paste
• 1 medium Yukon Gold potato, peeled and diced
• 1 sprig fresh rosemary
• 1 bay leaf
• 2 cans (15 oz each / 425 g each) cannellini beans, drained and rinsed
• 5 cups (1.2 L) vegetable broth, plus more as needed
• 1 bunch cavolo nero or lacinato kale, stems removed and leaves sliced
• 3 cups (210 g) thinly sliced Savoy cabbage
• 5 oz (140 g) stale country bread, torn into rough chunks
• 1 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon black pepper, plus more for serving