In a pot of boiling salted water, cook the pasta until al dente. Save 250 ml (1 cup) cooking water. Drain the pasta and set aside.
Meanwhile, in a skillet over medium-high heat, brown the pancetta in the oil. Add the garlic and continue cooking for 1 minute. Add the broth, leeks and chicken. Bring to a boil and add the pasta, cheese and parsley. Toss well to combine, adding a small amount of the reserved cooking water if needed. Adjust the seasoning.