In a large skillet heat oil over medium-low heat. Add leeks, salt and pepper. Cook until soft, about 10 minutes. Add beans, broth and sage. With a potato masher, mash about 1/3 of the beans. Bring to a boil, reduce to a simmer. Cook until lightly thickened, about 5 minutes. Cook pasta for 2 minutes less than package directs. Drain. Bring bean and leek sauce to a simmer. Add lemon juice and parmesan. Mix. Add pasta and cook 2 minutes, stirring until heated through. Serve sprinkled with parsley.
Per serving - 360 calories, 7 g fat (17% calories from fat), 16 g protein, 62 g carbohydrate, 9 g fiber, 0 mg cholesterol, 332 mg sodium