Pasta E Fagioli (Pasta And Beans Soup)

Ingredients

• 4 oz diced pancetta
• 3 tablespoons extra-virgin olive oil (divided)
• 1 medium yellow onion
• 2 carrots (chopped)
• 2 ribs of celery (chopped)
• ½ cup chopped fennel bulb
• 4 cloves garlic
• ½ teaspoon fennel seed (crushed to release oils)
• 1 teaspoon kosher salt (divided)
• 1 tablespoon fresh rosemary (finely chopped, plus more for serving)
• ⅛ teaspoon red pepper flakes
• 6 ounces tomato paste (about ¼ cup)
• 6 cups chicken stock
• 1 bay leaf
• 2 15 ounce cans cannellini beans (drained and rinsed)
• 2 cups kale (slivered)
• 1 inch chunk Parmesan rind
• 6 ounces uncooked ditalini pasta
• 1 tablespoon butter
• grated Parmesan cheese (for serving)