Preheat oven to 375 degrees F. Spray a large, 13x9-inch casserole baking dish with nonstick cooking spray and set aside.
Boil water in a pot and season generously with salt. Cook pasta to al dente according to package directions, adding the broccoli during the last 2 minutes. Drain well and set aside.
Meanwhile, in a large bowl, combine cream soup, milk lemon juice, onion powder, paprika and black pepper. Stir in cheddar cheese, then chicken breast. Finally stir in the pasta and broccoli, making sure it is well drained.
Pour mixture into the baking dish.
In a small bowl, combine panko, melted butter and parsley. Sprinkle on top of the casserole.
Bake, uncovered, in the preheated oven for 25-30 minutes or until breadcrumbs are golden and casserole is bubbly.