You can use pre-cooked chicken if you have some on hand or prefer to pick up a rotisserie chicken at the store. If you're starting from scratch with the chicken, you can cook it any way you like and then shred it. I find the easiest way to get to cooked chicken is to cut your chicken breast in into 1 inch chunks and season with salt, pepper, and chili powder. Heat a tablespoon of olive oil in a large skillet and brown the chicken on all sides until cooked through. Remove the chicken from the pan to cool slightly. Once it's cool enough to handle, just pull the small pieces apart with your fingers. I did this while the onions and peppers were cooking.
Cook your pasta in well salted boiling water for about one minute less than the package instructs. Drain and set aside.
While the pasta is cooking, you can get on with your veggies. Add your onion and pepper to the pan recently vacated by the chicken. Cook for about five minutes over medium heat or until the veggies start to soften.
Add the garlic and corn to the pan and cook for another minute until fragrant.
Add the now shredded chicken back to the skillet and turn the heat down to low. Add the cumin, chili powder, and cayenne, and stir to combine. Once the pasta is cooked and drained, you can turn the heat off under your skillet and stir in the macaroni to this mixture as well.
In a small sauce pan over medium low heat, melt your better. Stir in flour and let it cook for 1 minute or until it starts to smell nutty. Using a whisk, add the milk a bit at a time, whisking to keep things smooth. You may need to turn up the heat. You want to keep it gently bubbling if you can. Allow this mixture to cook, stirring frequently, until it starts to thicken. This could take five minutes.
Add in pepper jack and cheddar, stirring until smooth. Add the cheese sauce to everything else in the skillet and stir to combine.
Transfer your mac and cheese to the baking dish. Sprinkle the parmesan over the top and bake for about 20 minutes until everythings hot and happy and lightly browned around the edges. Allow it to cool for about 10 minutes before serving.