Brown kielbasa in oil and butter in a large skillet. Add the potatoes, carrots, celery and onion. Cook and stir for 3 minutes over medium heat. Transfer to a 4- or 5-qt. slow cooker. Stir in the broth, lentils, tomatoes, bay leaf, pepper and salt.
Cover and cook on low for 8-10 hours or until lentils are tender. Cook pasta according to package directions; drain. Stir pasta into slow cooker. Discard bay leaf. Sprinkle servings with cheese. Yield: 8 servings.