If time allows, always try to marinate your chicken. Throw them in a bag of Italian dressing and let sit overnight or even a few hours will help your chicken to be tender and full of flavor.
Cook pasta as directed. Drain and set aside.
While pasta is cooking, heat 1 - 2 TB of oil in a skillet on medium heat.
Slice your marinated chicken in half so they are thinner pieces. This will help them cook through evenly.
In a bowl mix salt, pepper, thyme and poultry seasoning and rub it on all sides of your chicken breasts. Add chicken to hot oil and cook on both sides until done (about 15-20 minutes). Remove to a plate to let cool.
While chicken is cooling, preheat your oven to 350 and start on your sauce. In a separate large skillet melt the butter; add garlic and cook for 1 - 2 minutes.
Using a wire whisk, mix in flour and stir until bubbly. Mix in half & half and milk, stir to combine. Bring to a boil and then reduce to low heat and simmer for 5 minutes.
With your whisk, mix in 1½ cup of cheese. Cook an additional 5 minutes until sauce starts to thicken. Remove sauce from heat.
Cut your cooked chicken into bite size pieces and add to a large bowl. Add the pasta to your bowl and then the sauce. Mix everything to combine.
Spray a 9x13 baking pan with non stick spray. Add the pasta mixture to the pan and sprinkle with an additional 1½ cup of cheese.
Sprinkle with pepper and bake for 30 minutes or until bubbly and golden brown.