In a large skillet, melt 2 tablespoons of butter over medium heat. Add the bite-sized chicken pieces and cook until browned on all sides, about 5-7 minutes. Use a wooden spoon to stir occasionally for even cooking.
Once the chicken is browned, add the diced onion and minced garlic to the skillet. Sauté until the onion is translucent and the garlic is fragrant, about 3-4 minutes. Stir in the Italian seasoning and season with salt and pepper to taste.
Pour the marinara sauce into the skillet with the chicken and stir to combine. Allow the mixture to simmer for a couple of minutes, letting the flavors meld together.
Preheat your oven to 375°F (190°C). In a large baking dish, spread half of the marinara chicken mixture on the bottom. Sprinkle half of the dry pasta evenly over the sauce. Layer half of the shredded mozzarella cheese on top.
Add the remaining marinara chicken mixture over the cheese, followed by the rest of the dry pasta. Finish with the remaining mozzarella cheese and sprinkle the grated parmesan cheese on top.
In a small bowl, melt the remaining 2 tablespoons of butter and mix in the panko breadcrumbs until coated. Sprinkle this mixture evenly over the top of the pasta for a crunchy topping.
Cover the baking dish with aluminum foil and bake in the preheated oven for 25 minutes. After that, remove the foil and bake for an additional 15-20 minutes or until the cheese is bubbly and golden brown.
Once baked, remove the dish from the oven and let it sit for 5 minutes. If desired, garnish with fresh chopped basil before serving. Enjoy your delicious No-Boil Chicken Parmesan Pasta!