Preheat your oven to 350 degrees F. Grease a 2-quart casserole dish and set aside.

Bring a large pot of salted water to a boil. Cook pasta al dente according to package directions. Add broccoli florets to the boiling water during the last 2 minutes of cooking. Drain both together very well, shaking the colander to remove all excess water.

In a mixing bowl, combine the Alfredo sauce, 1 cup cheddar, swiss cheese, garlic powder, and dry mustard powder. Stir until smooth and fully combined.

In a large bowl, stir together the drained pasta, broccoli, chopped chicken, and sauce mixture until everything is evenly coated. Transfer to the prepared casserole dish and spread into an even layer.

In a small bowl, mix together the Panko bread crumbs, melted butter, parsley, and remaining 1/2 cup cheddar cheese. Sprinkle the topping evenly across the casserole.

Bake uncovered for 35 minutes until the topping is golden brown and the edges are bubbling. Let the casserole rest for 5 minutes before serving.