Cook the pasta according to package instructions. Drain and set aside.
Preheat the oven to 400 F. In a large mixing bowl, combine the shredded chicken, broccoli, garlic powder, red pepper flakes, Italian seasoning, salt and pepper and Alfredo sauce. Mix to combine.
To a 9-inch by 13-inch rectangular baking dish, add the cooked pasta then top with the chicken alfredo mixture from the mixing bowl. Top with the cheese.
Bake at 400 F for 20-25 minutes until bubbly and golden. Top with fresh basil and parsley flakes for serving.
Notes
Stop cooking the pasta and drain it before it reaches al dente firmness to keep it from turning mushy in the casserole.
Cut the broccoli into small, bite-sized pieces so it cooks evenly and blends well with the pasta and chicken.
Stir the chicken, broccoli, and Alfredo sauce well before adding it to the baking dish so the casserole stays creamy and evenly coated.
If the cheese starts to brown before the casserole is fully heated through, loosely tent the dish with foil to keep the cheese melty without over-browning.