Butterfly the chicken then cut it in half lengthwise to make thinner cutlets. Add the chicken and the marinade ingredients to a large Ziploc bag and place in the fridge for 30 minutes.
Meanwhile, make the dressing and set it aside until needed. Prep your cilantro, onion, cheddar, and avocado.
Start boiling a large salted pot of water. Cook pasta according to package directions.
Preheat your BBQ/grill to high heat. Reduce heat to medium-high and cook the chicken for about 4 minutes/side or until it's cooked through but not overdone. Brush both sides of each piece of chicken with the BBQ sauce as needed.
When the pasta is cooked, drain it and rinse it with cool water. Make sure it's drained thoroughly. Add it to a large bowl.
Add the cilantro, onion, cheddar, avocado, and dressing to the pasta. Toss. Slice the chicken and top the pasta salad with it after it cools for a few minutes. Gently mix the chicken in if desired. Season the salad with extra salt & pepper if needed.