Add the chicken to a bowl and sprinkle on the Italian dressing, olive oil, and Italian seasoning. Mix well. Let marinate from an hour up to 24 hours.
Heat oven to 350 F. Lightly grease or spray a deep 9"x13" baking dish.
Bring a pot of salted water to boil and cook the pasta. Drain it and set it aside in the same pot you cooked it in.
Heat a skillet over medium high heat and add the chicken and garlic. Cook until about half done. Then add to the pasta and stir.
Place the skillet back on the stove and lower the heat. Melt the butter, then whisk in the flour and cook, stirring constantly, until foamy and light.
Whisk in the half and half. Keep stirring until the mixture thickens (bump up the heat a little if needed).
Whisk in the salt and pepper.
Stir in the cream cheese and let it melt.
Pour the Alfredo sauce into the pasta and chicken.
Add half of the Italian Cheese blend and half of the parmesan. Stir in well. Pour into the prepared baking dish and top with the remaining cheeses.
Bake for 25-30 minutes, until bubbling and golden.
Serve immediately.