Cook pasta to package directions
Meanwhile, in a large skillet over medium heat, cook the chicken, onion, salt and pepper in the oil until chicken is no longer pink
Stir in alfredo sauce; bring to a boil
Stir in cheese, salsa, milk and taco seasoning
Drain pasta, toss with chicken mixture
Place into a 9×13 inch pan coated with pan spray
Cover and bake at 350° for 30-35 minutes or until bubbly