Heat the oven to 425°F. Toss squash with 1 tablespoon oil and 1/4 teaspoon salt on a rimmed sheet, then roast for 20 to 25 minutes, turning once, until browned and tender.
Meanwhile, heat remaining oil in a soup pot over medium heat. Cook fennel and onion for 8 minutes, then stir in garlic for 30 seconds.
Add tomatoes with their juices, broth, oregano, beans and remaining salt. Bring to a simmer and cook for 10 minutes.
Stir in farfalline and simmer for 4 minutes, then add kale and cook for 5 to 7 minutes more until pasta is tender.
Fold in roasted squash, lemon juice and pepper and warm for 2 minutes. Divide among 6 bowls while the pasta still has a little bite.