Set a pot of water to boil for the pasta while you cook the other ingredients.
Heat a large pan over medium heat.
Add just enough oil to coat the bottom and cook the chicken about two minutes on each side, until no longer pink.
Remove the chicken to a heat-safe bowl or dish and place in the oven at 250F to keep warm.
Add a little more oil to the same pan, reduce the heat to medium-low, and add the onion and garlic.
Allow to saute for a minute or two.
You can also add a splash of white wine if you have a lot of brown bits on the bottom of your pan.
Add the bag of frozen vegetables, stir to combine with the onion and garlic, and allow to cook over medium heat until the vegetables are cooked, but still crisp.
Add chicken pieces and season with red pepper, salt, and pepper.
Meanwhile, add the pasta to the boiling water and cook according to package instructions until al dente.
Drain well and remove to a large serving bowl.
Add the butter and allow it to melt, stirring to coat the pasta.
Add chicken and vegetable mixture and parmesan cheese, reserving a handful of the cheese for garnish.
Mix until well combined and top with remaining cheese.
Serve immediately.
Note: This recipe makes four generous servings; it can easily be stretched to serve six with the inclusion of bread and/or a salad.