Bring large pot of salted water to a boil. Add broccoli rabe; simmer 5 minutes. Using a skimmer, remove broccoli rabe and set aside. Return water to a boil, or discard and bring a fresh pot of salted water to a boil.
Cook cavatelli following package directions. Drain.
Meanwhile, heat olive oil in large skillet over medium-high heat. Add sausage and onion; cook 5 minutes or until no longer pink, breaking up sausage with wooden spoon. Add garlic and cooked broccoli rabe; cook 5 minutes. Add chicken broth and salt and pepper. Bring to a simmer. Add parsley and remove from heat.
Pour sausage mixture over cooked pasta. Sprinkle with cheese and serve.