1. Heat a grill to high. Grill or broil the chicken until it reaches a minimum internal temperature of 165 degrees F (5 minutes per side).
2. Transfer the chicken to a cutting board and let rest 5 minutes. Slice into strips.
3. In a large frying pan, heat the olive oil over medium heat. Add the onions and mushrooms and saute until tender (5-10 minutes).
4. Stir in the white beans, garlic, basil, grilled chicken, and cooked pasta. If pasta is cold, heat on low until mixture is warm.
5. Top with Parmesan and pepper to serve.